Use modern website workflow with up to date sphinx version

.github/workflows/website.yml

@@ -12,24 +12,39 @@ jobs:
   website:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
-    - name: Generate sphinx website
-      uses: ax3l/sphinx-action@newer-sphinx
+    - name: Clone website repository on current branch
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+    - name: Clone website repository on gh-pages branch
+      uses: actions/checkout@v4
       with:
-        pre-build-command: "pip3 -q install sphinx-material 'sphinxcontrib-bibtex<2.0.0'"
-        docs-folder: .
+        ref: gh-pages
+        fetch-depth: 0
+        path: _build/html
+    - name: Install dependencies
+      run: |
+        pip3 -q install sphinx-material sphinxcontrib-bibtex
+    - name: Generate sphinx website
+      run: |
+        rm -rf _build/html/* && python3 -m sphinx -W -b html . _build/html
     - name: Fix permissions and add CNAME file
       run: |
         sudo chown $USER _build -R
         echo "www.rbnicsproject.org" > _build/html/CNAME
     - name: Deploy to GitHub pages
       if: github.repository == 'RBniCS/rbnicsproject.org' && github.ref == 'refs/heads/main'
-      uses: peaceiris/actions-gh-pages@v3
-      with:
-        github_token: ${{ secrets.GITHUB_TOKEN }}
-        publish_dir: _build/html
-        user_name: 'GitHub Actions'
-        user_email: '41898282+github-actions[bot]@users.noreply.github.com'
+      run: |
+        SHA_SHORT=$(git rev-parse --short HEAD)
+        pushd _build/html
+        git config user.name "GitHub Actions"
+        git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+        git add .
+        git pull origin gh-pages
+        [ -n "$(git status --porcelain=v1 2>/dev/null)" ] && git commit -m "deploy: ${SHA_SHORT}"
+        git push origin gh-pages
+        popd
+      shell: bash
     - name: Deploy to GitHub artifacts
       if: github.repository == 'RBniCS/rbnicsproject.org' && github.ref != 'refs/heads/main'
       uses: actions/upload-artifact@v3