[gha][canary] allow external contributors build/lint

Author: rustielin

.github/workflows/ci.yml

@@ -7,6 +7,7 @@ on:
   pull_request_target:
     branches:
       - 06-18-_gha_allow_external_contributors_build_lint # canary for the PR that introduces pull_request_target
+      - 06-18-_gha_canary_allow_external_contributors_build_lint
 
 permissions:
   contents: read