run only if pull requests come from the same repo

Author: yifanyang

.github/workflows/smoke-tests.yml

@@ -4,6 +4,7 @@ on: [ pull_request ]
 
 jobs:
   smoke-tests:
+    if: github.event.pull_request.head.repo.full_name == github.repository
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3