Add asf-staged for deployment preview

[tuhaihe]

closes: #182

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[tuhaihe]

When Deploy to staging, an error happened:

  /usr/bin/git push origin asf-staging
  remote: Permission to apache/cloudberry-site.git denied to github-actions[bot].
  fatal: unable to access 'https://github.com/apache/cloudberry-site.git/': The requested URL returned error: 403
  Error: Action failed with "The process '/usr/bin/git' failed with exit code 128"

However, have already added the write permissions to the job:

    permissions:
      contents: write

[tuhaihe]

If all goes well, we can visit cloudberry.staged.apache.org to preview the changes to the site.