Merge pull request #4555 from mozilla/MNTOR-3221

MNTOR-3221: avoid recomment on the same PR

.github/workflows/preview_deploy_gcp.yml

@@ -88,3 +88,6 @@ jobs:
           GITHUB_TOKEN: ${{ github.token }}
           message: |
             Preview URL :rocket: : ${{ steps.deploy.outputs.url }}
+          comment_tag: preview_url
+          create_if_not_exists: true
+