ci: coveralls, pipx, and allow workflow_dispatch (#532)

* ci: pipx and allow workflow_dispatch

* fix: coveralls 3 detection broken

TheKevJames/coveralls-python#252

.github/workflows/ci.yml

@@ -1,6 +1,7 @@
 name: CI
 
 on:
+  workflow_dispatch:
   push:
     branches:
     - master
@@ -65,7 +66,7 @@ jobs:
 
     - name: Upload coverage
       if: matrix.python-version != '2.7' && matrix.python-version != 'pypy-2.7'
-      run: coveralls
+      run: coveralls --service=github
       env:
         COVERALLS_PARALLEL: true
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -77,11 +78,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - uses: actions/setup-python@v2
-    - name: Install dependencies
-      run: python -m pip install build
     - name: Build SDist and wheel
-      run: python -m build
+      run: pipx run --spec build pyproject-build
     - uses: actions/upload-artifact@v2
       with:
         path: dist/*