Use actions/deploy-pages@v4 action instead of gh-pages branch

Using this action updates the online HTML pages without needing to
commit them to a Git branch. This will avoid the gh-pages branch growing
ever larger and larger with all the generated HTML pages.

Author: jwakely

.github/workflows/deploy.yml

@@ -16,8 +16,14 @@ concurrency:
   group: "pages"
   cancel-in-progress: false
 
+# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
 jobs:
-  update-html-pages:
+  generate-html-pages:
     runs-on: ubuntu-latest
 
     steps:
@@ -38,34 +44,20 @@ jobs:
     - name: Generate HTML lists
       run: make lists
 
-    # Clone the gh-pages branch into a sub-directory.
-    # The default fetch-depth:1 is OK for this step.
-    - name: Clone repo again in order to push
-      uses: actions/checkout@v5
+    # Make the HTML pages available the the deploy job below.
+    - name: Upload artifacts
+      uses: actions/upload-pages-artifact@v3
       with:
-        ref: 'gh-pages'
-        path: 'gh-pages'
-        clean: 'false'
+        patch: mailing/
 
-    - name: Update online pages
-      run: |
-        : Push new HTML files to gh-pages branch
-        mv mailing/*.html gh-pages/
-        rmdir mailing
-        cd gh-pages
-        git config user.name "github-actions"
-        git config user.email "[email protected]"
-        # Stage any changes to the individual issues (including new files):
-        git add issue*.html
-        # This only compares the staged changes, so ignores new timestamps
-        # in the lwg-*.html files. The commit -a will pick those up though.
-        printf '\nChecking HTML issues for changes ...\n'
-        if git diff --cached --exit-code --name-status ; then
-          echo 'No changes, not publishing new lists.'
-        else
-          printf '\nCommitting the changes above:\n'
-          git commit -a -m 'Automatic update from GitHub Actions workflow'
-          printf '\nPushing to the gh-pages branch:\n'
-          git push
-        fi
-        cd ..
+  # Deployment job
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    needs: generate-html-pages
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4