Update docs.yml

Author: sol1105

.github/workflows/docs.yml

@@ -25,7 +25,7 @@ jobs:
         run: mkdocs build --clean
 
       - name: Deploy to GitHub Pages
-        uses: peaceiris/actions-gh-pages@v6
+        uses: peaceiris/actions-gh-pages@v3
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./site