labeler: run when marked as "ready for review" (#15436)

.github/workflows/labeler.yml

@@ -1,5 +1,9 @@
 name: PR Labeler
-on: pull_request_target
+on: 
+  pull_request_target:
+  pull_request:
+    types:
+      - ready_for_review
 permissions:
   pull-requests: write
 jobs: