[CI][Github] Only run CI Checks Workflow on Push for Main

Currently the check-ci workflow runs on the push event as well
regardless of the branch which means the workflow runs twice on stacked
PRs. Not a big deal, but a bit weird to see the same workflow running
twice in a PR.

Author: boomanaiden154

.github/workflows/check-ci.yml

@@ -5,6 +5,8 @@ permissions:
 
 on:
   push:
+    branches:
+     - main
     paths:
      - '.ci/**'
      - '.github/workflows/check-ci.yml'