[actions] switch Automatic Rebase workflow to `pull_request_target` event
diff --git a/.github/workflows/rebase.yml b/.github/workflows/rebase.yml
index 844cbba..027aed0 100644
--- a/.github/workflows/rebase.yml
+++ b/.github/workflows/rebase.yml
@@ -1,6 +1,6 @@
 name: Automatic Rebase
 
-on: [pull_request]
+on: [pull_request_target]
 
 jobs:
   _: