update branch

Author: tuhaihe

.github/workflows/publish-cloudberry-site.yml

@@ -68,7 +68,7 @@ jobs:
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./build
-          publish_branch: preview/${{ github.event.pull_request.number }}
+          publish_branch: preview
 
       # Deploy to asf-site for production
       - name: Deploy to production