fix: downgrade actions/deploy-pages from v5 to v4

v5 does not exist yet, causing workflow failure.

Author: WangSimiao2000

.github/workflows/pages-deploy.yml

@@ -94,4 +94,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v5
+        uses: actions/deploy-pages@v4