ci: add a condition to check if event is pull request

Author: LuqiPan

.github/workflows/build-deploy-doc.yml

@@ -56,6 +56,7 @@ jobs:
         command: pages deploy --project-name=documentation dist/
 
     - name: Comment with preview URL
+      if: github.event_name == 'pull_request'
       uses: actions/github-script@v7
       with:
         script: |