ci: upgrade peaceiris/actions-gh-pages to v4 (Node.js 20)

Author: Tanisha127

.github/workflows/latest_docs.yml

@@ -30,7 +30,7 @@ jobs:
         run: poetry run sphinx-build -b html docs/source docs/build/html
 
       - name: Deploy HTML to GitHub Pages 🚀
-        uses: peaceiris/actions-gh-pages@v3.9.3
+        uses: peaceiris/actions-gh-pages@v4
         with:
           publish_branch: gh-pages
           github_token: ${{ secrets.GITHUB_TOKEN }}