Add a draft of a release workflow

.github/workflows/release.yml

@@ -0,0 +1,115 @@
+# Based on a packaging guide at https://packaging.python.org/en/latest/guides/publishing-package-distribution-releases-using-github-actions-ci-cd-workflows/
+name: Release
+
+on:
+  push:
+    branches: [main]
+    tags: ["*"]
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Build distribution
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+
+      - name: Install pypa/build
+        run: |
+          python3 -m pip install build
+
+      - name: Build a binary wheel and a source tarball
+        run: |
+          python3 -m build
+
+      - name: Store the distribution packages
+        uses: actions/upload-artifact@v4
+        with:
+          name: python-package-distributions
+          path: dist/
+
+  publish-to-testpypi:
+    name: Publish distribution to TestPyPI
+    needs: [build]
+    runs-on: ubuntu-latest
+
+    environment:
+      name: test-release
+      url: https://test.pypi.org/p/defer-imports
+
+    permissions:
+      id-token: write  # IMPORTANT: mandatory for trusted publishing
+
+    steps:
+    - name: Download all the dists
+      uses: actions/download-artifact@v4
+      with:
+        name: python-package-distributions
+        path: dist/
+
+    - name: Publish package distributions to TestPyPI
+      uses: pypa/gh-action-pypi-publish@release/v1
+      with:
+        repository-url: https://test.pypi.org/legacy/
+
+  publish-to-pypi:
+    name: Publish distribution to PyPI
+    needs: [publish-to-testpypi]
+    runs-on: ubuntu-latest
+
+    environment:
+      name: release
+      url: https://pypi.org/p/defer-imports
+
+    permissions:
+      id-token: write  # IMPORTANT: mandatory for trusted publishing
+
+    steps:
+    - name: Download all the dists
+      uses: actions/download-artifact@v4
+      with:
+        name: python-package-distributions
+        path: dist/
+
+    - name: Publish package distributions to PyPI
+      uses: pypa/gh-action-pypi-publish@release/v1
+
+  release-on-github:
+    name: Upload distributions to GitHub Release
+    needs: [publish-to-pypi]
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: write  # IMPORTANT: mandatory for making GitHub Releases
+
+    steps:
+    - name: Download all the dists
+      uses: actions/download-artifact@v4
+      with:
+        name: python-package-distributions
+        path: dist/
+
+    - name: Create GitHub Release
+      env:
+        GITHUB_TOKEN: ${{ github.token }}
+      run: >-
+        gh release create
+        '${{ github.ref_name }}'
+        --repo '${{ github.repository }}'
+        --notes ""
+
+    - name: Upload artifacts to GitHub Release
+      env:
+        GITHUB_TOKEN: ${{ github.token }}
+      run: >-
+        gh release upload
+        '${{ github.ref_name }}' dist/**
+        --repo '${{ github.repository }}'