Update demo.yml

Author: Kanahiro

.github/workflows/demo.yml

@@ -11,7 +11,7 @@ on:
 
 permissions:
   id-token: write
-  contents: read
+  contents: write
   pull-requests: write
 
 jobs:
@@ -38,7 +38,7 @@ jobs:
               run: touch ./demo/.nojekyll
 
             - name: deploy
-              uses: peaceiris/actions-gh-pages@v3
+              uses: peaceiris/actions-gh-pages@v4
               with:
                   github_token: ${{ secrets.GITHUB_TOKEN }}
                   publish_dir: ./demo