Update label-on-approval.yml (#576)

Author: mxsm

.github/workflows/label-on-approval.yml

@@ -1,8 +1,8 @@
 name: Add Label on Approval
 
 on:
-  pull_request_target:
-    types: [opened, synchronize]
+  pull_request_review:
+    types: [submitted]
 
 permissions:
   issues: write