Revert "ci: assigner: only run on main branch"

This reverts commit 79356f1.

Author: nashif

.github/workflows/assigner.yml

@@ -9,6 +9,8 @@ on:
     - ready_for_review
     branches:
     - main
+    - collab-*
+    - v*-branch
   issues:
     types:
     - labeled