CI: Add "trusted publishing" workflow

.github/workflows/publish.yml

@@ -0,0 +1,43 @@
+name: Build and publish to PyPI
+on: push
+jobs:
+  build:
+    name: Build distribution
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3"
+    - name: Install "build"
+      run: |
+        python -m pip install build
+    - name: Build a binary wheel and a source tarball
+      run: python -m build
+    - name: Store the distribution packages
+      uses: actions/upload-artifact@v4
+      with:
+        name: dist
+        path: dist
+  publish:
+    name: Upload release to PyPI
+    if: startsWith(github.ref, 'refs/tags/')
+    needs:
+    - build
+    runs-on: ubuntu-latest
+    environment:
+      name: pypi
+      url: https://pypi.org/p/nbsphinx
+    permissions:
+      id-token: write
+    steps:
+    - name: Get the artifacts
+      uses: actions/download-artifact@v3
+      with:
+        name: dist
+        path: dist
+    - name: Publish package distributions to PyPI
+      uses: pypa/gh-action-pypi-publish@release/v1
+      with:
+        print-hash: true