Add ruff linting

.github/workflows/checks.yaml

@@ -0,0 +1,37 @@
+name: checks
+on: [push, pull_request]
+jobs:
+  deps:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ["3.8", "3.9", "3.10", "3.11"]
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install dependencies
+        run: |
+          python -m pip install pipenv
+          pipenv install --skip-lock  # this is what Elastic beanstalk uses
+  lint:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Setup Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: "3.11"
+
+      - name: Install dependencies
+        run: python3 -m pip install ".[dev]"
+
+      - name: Check style
+        run: python3 -m ruff check . && python3 -m ruff format --check .