Integrated the automated version bump code to the cirq plugin

.github/workflows/changelog_template.txt

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+# Release x.x.x-dev
+
+### New features since last release
+
+### Breaking changes
+
+### Improvements
+
+### Documentation
+
+### Bug fixes
+
+### Contributors
+
+This release contains contributions from (in alphabetical order):
+
+---

.github/workflows/post_release_version_bump.yml

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+name: Automated Release Version Bumps
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  post_release_version_bump:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v2
+
+      - name: Install Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.9'
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install pennylane
+
+      - name: Run version bump
+        run: >
+          python .github/workflows/vb_script.py
+          --version_path "./pennylane_cirq/_version.py"
+          --changelog_path "CHANGELOG.md" --post_release
+
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v3
+        with:
+          commit-message: post release version bump
+          title: Version Bump
+          body: updated changelog and _version.py
+          branch: post-release-version-bump
+          reviewers: rmoyard
+          base: main

.github/workflows/pre_release_version_bump.yml

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+name: Manually Triggered Version Bumps
+
+on:
+  workflow_dispatch:
+
+jobs:
+  pre_release_version_bump:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v2
+
+      - name: Install Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.9'
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install pennylane
+
+      - name: Run version bump
+        run: >
+          python .github/workflows/vb_script.py
+          --version_path "./pennylane_cirq/_version.py"
+          --changelog_path "CHANGELOG.md" --pre_release
+
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v3
+        with:
+          commit-message: pre release version bump
+          title: Version Bump
+          body: updated changelog and _version.py
+          branch: pre-release-version-bump
+          reviewers: rmoyard
+          base: main

.github/workflows/vb_script.py

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+"""This module implements the logic required to automatically bump the version number in the version file and update the changelog accordingly."""
+# Copyright 2018-2021 Xanadu Quantum Technologies Inc.
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import argparse
+import pennylane as qml
+pl_version = '"' + qml.version() + '"'
+
+
+def bump_version(version_line, pre_release):
+    """ A helper function which takes the current version string and
+    replaces it with the bumped version depending on the pre/post
+    release flag.
+
+    Example:
+        Assume that we have PennyLane version 0.18.0 as the latest release on PyPi.
+
+        Pre-release:
+        We gather the version number for the latest of PennyLane release (i.e., v0.18.0) and increment the middle value
+        to obtain the version of the plugin that we'll release: v0.19.0.
+
+        Post-release:
+        We have just released the v0.19.0 version of the plugin and have v0.19.0 set as the version number.
+        We are entering a new development phase of the plugin attached to the next release, so we increment the
+        version number (0.20.0) and add the "-dev" suffix (0.20.0-dev).
+
+    Args:
+         version_line (string): The string containing the current
+            version of the plugin.
+         pre_release (bool): A flag which determines if this is a
+            pre-release or post-release version bump.
+
+    Returns:
+        resultant_line (string): A string of the same form as the version line
+        with the version number replaced with the bumped version.
+        bumped_version (string): The bumped version string.
+    """
+    data = version_line.split(" ")
+    curr_version = data[-1]
+
+    if pre_release:
+        curr_version = pl_version  # get current Pennylane version
+
+    split_version = curr_version.split(".")  # "0.17.0" --> ["0,17,0"]
+    split_version[1] = str(int(split_version[1]) + 1)  # take middle value and cast as int and bump it by 1
+
+    if not pre_release:
+        split_version[2] = split_version[2].replace('"', '-dev"')  # add -dev, ["0,18,0"] --> ["0,18,0-dev"]
+
+    bumped_version = ".".join(split_version)
+    data[-1] = bumped_version
+    return " ".join(data), bumped_version
+
+
+def update_version_file(path, pre_release=True):
+    """ Updates the __version__ attribute in a specific version file.
+
+    Args:
+        path (str): The path to the version file.
+        pre_release (bool): A flag which determines if this is a
+            pre-release or post-release version bump.
+
+    Return:
+        new_version (str): The bumped version string.
+    """
+    with open(path, 'r', encoding="utf8") as f:
+        lines = f.readlines()
+
+    with open(path, 'w', encoding="utf8") as f:
+        for line in lines:
+            if "__version__" in line.split(' '):
+                new_line, new_version = bump_version(line, pre_release)
+                f.write(new_line)
+            else:
+                f.write(line)
+    return new_version
+
+
+def remove_empty_headers(lines):
+    """ Takes a paragraph (list of strings) and removes sections which are empty.
+    Where a section begins with a header (### Header_Title).
+
+    Args:
+        lines (list[string]): The paragraph containing the changelog sections.
+
+    Returns:
+        cleaned_lines (list[string]): The paragraph with empty sections removed.
+    """
+    cleaned_lines = []
+    pntr1 = 0
+
+    while pntr1 < len(lines):
+        is_empty = True
+        for pntr2 in range(pntr1 + 1, len(lines)):
+            line2 = lines[pntr2]
+
+            if (len(line2) >= 4) and (line2[:4] == "### "):
+                if (pntr1 == 0) or (not is_empty):
+                    cleaned_lines.extend(lines[pntr1:pntr2])  # keep these sections!
+
+                pntr1 = pntr2
+                is_empty = True  # reset the empty flag
+
+            elif line2 == '\n':
+                pass
+
+            else:
+                is_empty = False
+
+        cleaned_lines.extend(lines[pntr1:pntr1+1])
+        pntr1 += 1
+
+    return cleaned_lines
+
+
+def update_changelog(path, new_version, pre_release=True):
+    """ Updates the Changelog file depending on whether it's a pre-release
+    or post-release version bump.
+
+    Args:
+        path (str): The path to the changelog file.
+        new_version (str): The bumped version string.
+        pre_release (bool): A flag which determines if this is a
+            pre-release or post-release version bump.
+    """
+    with open(path, 'r', encoding="utf8") as f:
+        lines = f.readlines()
+        end_of_section_index = 0
+        for index, line in enumerate(lines):
+            if (len(line) >= 3) and (line[:3] == "---"):
+                end_of_section_index = index
+                break
+
+    with open(path, 'w', encoding="utf8") as f:
+        if not pre_release:  # post_release append template to top of the changelog
+            with open("./.github/workflows/changelog_template.txt", 'r', encoding="utf8") as template_f:
+                template_lines = template_f.readlines()
+                template_lines[0] = template_lines[0].replace('x.x.x-dev', new_version)
+                f.writelines(template_lines)
+                f.writelines(lines)
+
+        else:  # pre_release update the release header and remove any empty headers
+            # update release header
+            line = lines[0]
+            split_line = line.split(" ")
+            split_line[-1] = new_version  # replace version (split_line = [#, Release, 0.17.0-dev])
+            new_line = " ".join(split_line) + '\n'
+            f.write(new_line)
+
+            # remover empty headers
+            cleaned_lines = remove_empty_headers(lines[1:end_of_section_index])
+            f.writelines(cleaned_lines)
+
+            # keep the rest of the changelog
+            rest_of_changelog_lines = lines[end_of_section_index:]
+            f.writelines(rest_of_changelog_lines)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--version_path", type=str, required=True, help="Path to the _version.py file")
+    parser.add_argument("--changelog_path", type=str, required=True, help="Path to the changelog")
+    parser.add_argument("--pre_release", dest="release_status", action="store_true",
+                        help="True if this is a pre-release version bump, False if it is post release")
+    parser.add_argument("--post_release", dest="release_status", action="store_false",
+                        help="True if this is a pre-release version bump, False if it is post release")
+
+    args = parser.parse_args()
+    updated_version = update_version_file(args.version_path, args.release_status)
+    update_changelog(args.changelog_path, updated_version, args.release_status)