Merge pull request #520 from PHPCSStandards/feature/ghactions-mergeconflicts-check-v4-branch-too

GH Actions/merge conflicts: also check PRs for the 4.0 branch

Author: jrfnl

.github/workflows/label-merge-conflicts.yml

@@ -5,6 +5,7 @@ on:
   push:
     branches:
       - master
+      - 4.0
   # Check conflicts in new PRs and for resolved conflicts due to an open PR being updated.
   pull_request_target:
     types: