CI: Avoid running on 'push' in mirrors / forks (#110063)

* CI: Avoid running on 'push' in mirrors / forks

* use single quotes

.github/workflows/shellcheck.yml

@@ -15,6 +15,8 @@ permissions: {}
 
 jobs:
   shellcheck:
+    # Run on `grafana/grafana` main branch, or on pull requests to prevent double-running on mirrors
+    if: (github.event_name == 'pull_request' || (github.event_name == 'push' && github.repository == 'grafana/grafana'))
     name: Shellcheck scripts
     runs-on: ubuntu-latest
     permissions: