Update peaceiris/actions-gh-pages action to v4

Author: renovate[bot]

.github/workflows/gh-pages.yml

@@ -24,7 +24,7 @@ jobs:
         run: hugo --minify
 
       - name: Deploy
-        uses: peaceiris/actions-gh-pages@v3
+        uses: peaceiris/actions-gh-pages@v4
         if: github.ref == 'refs/heads/main'
         with:
           deploy_key: ${{ secrets.MISCORD_GH_PAGES }}