restrict workflow to master* branches

Author: benieric

.github/workflows/codebuild-ci.yml

@@ -1,6 +1,8 @@
 name: PR Checks
 on:
     pull_request_target:
+        branches:
+            - "master*"
 
 concurrency:
     group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.head_ref }}