Update cherry-picker.yml to include the security vulnerability fix (#23635)

This is in regards to
https://github.com/bazelbuild/bazel/commit/55535cbb9a97d6be66e41a78f66ffeee678d4fb1

.github/workflows/cherry-picker.yml

 name: cherry-picker
 
 on:
-  pull_request_target:
+  pull_request:
     types: [closed]
+    branches: [master]
   issues:
     types: [closed, milestoned]