fix(ci): update GitHub Pages deployment to use newer actions and permissions

- Add explicit permissions for GitHub Pages deployment:
  - contents: read - for repository access
  - pages: write - for Pages deployment
  - id-token: write - for secure authentication

- Replace deprecated peaceiris/actions-gh-pages with modern GitHub Actions:
  - actions/configure-pages@v4 for Pages setup
  - actions/upload-pages-artifact@v3 for artifact upload
  - actions/deploy-pages@v4 for deployment

- Add github-pages environment configuration for proper deployment tracking

This resolves the "Permission denied" error when deploying documentation
to GitHub Pages. The new approach uses GitHub's built-in authentication
instead of requiring manual token configuration.

Fixes: remote: Permission to OpenPRoT/openprot.git denied to github-actions[bot]

Author: rusty1968

.github/workflows/docs.yml

@@ -8,13 +8,21 @@ on:
   pull_request:
     branches: [ main ]
 
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
 env:
   CARGO_TERM_COLOR: always
 
 jobs:
   docs:
     name: Documentation
     runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
     steps:
     - uses: actions/checkout@v4
 
@@ -41,10 +49,17 @@ jobs:
         cargo deadlinks --check-http
       continue-on-error: true
 
-    - name: Deploy documentation to GitHub Pages
+    - name: Setup Pages
+      if: github.ref == 'refs/heads/main'
+      uses: actions/configure-pages@v4
+      
+    - name: Upload artifact
       if: github.ref == 'refs/heads/main'
-      uses: peaceiris/actions-gh-pages@v3
+      uses: actions/upload-pages-artifact@v3
       with:
-        github_token: ${{ secrets.GITHUB_TOKEN }}
-        publish_dir: ./target/doc
-        force_orphan: true
+        path: ./target/doc
+        
+    - name: Deploy to GitHub Pages
+      if: github.ref == 'refs/heads/main'
+      id: deployment
+      uses: actions/deploy-pages@v4