Avoid CI failures in forks

When contributors fork the repo, they get GH actions that run when they push code to their forks. This change prevents GH Action "release" job failures. Example failure: https://github.com/shestee/mockito/actions/runs/375185562

.github/workflows/ci.yml

@@ -74,6 +74,7 @@ jobs:
 
     if: github.event_name == 'push'
         && github.ref == 'refs/heads/release/3.x'
+        && github.repository == 'mockito/mockito'
         && !contains(toJSON(github.event.commits.*.message), '[skip release]')
 
     steps: