CI: Publish each master commit with a unique version on TestPyPI

This follows commit 7d52df7 "CI: Ignore version duplicates when
publishing to TestPyPI" with a better design:
- Only publish builds from `master` branch on TestPyPI.
- Version every non-tag commit with a `.devN` suffix, e.g. `1.36.2.dev1`.
  This prevents duplicates on TestPyPI.
- `twine check` built packages.

See discussion at
#721 (comment)
for more details.

Author: adrienverge

.github/workflows/publish.yaml

@@ -8,19 +8,28 @@ jobs:
   build:
     name: Build distribution package
     runs-on: ubuntu-latest
-
     steps:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
+      - name: Fetch tags
+        run: git fetch --prune --unshallow --tags
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
           python-version: "3.x"
       - name: Install pypa/build
         run: python -m pip install --user build
+      - name: Set unique version for non-tag builds
+        if: ${{ ! startsWith(github.ref, 'refs/tags/') }}
+        run:  # add '.devN' to version
+          sed -i
+          "/^APP_VERSION = /s/'$/.dev$(git describe --tags | cut -d- -f2)'/"
+          yamllint/__init__.py
       - name: Build a binary wheel and a source tarball
         run: python -m build
+      - name: Twine check the distribution packages
+        run: python -Im twine check --strict dist/*
       - name: Store the distribution packages
         uses: actions/upload-artifact@v4
         with:
@@ -29,6 +38,7 @@ jobs:
 
   publish-to-testpypi:
     name: Publish distribution package to TestPyPI
+    if: github.ref == 'refs/heads/master'
     needs: build
     runs-on: ubuntu-latest
     environment:
@@ -46,7 +56,6 @@ jobs:
         uses: pypa/gh-action-pypi-publish@release/v1
         with:
           repository-url: https://test.pypi.org/legacy/
-          skip-existing: true
 
   publish-to-pypi:
     name: Publish distribution package to PyPI