try pull_request rather than pull_request_target

Author: tgross35

.github/workflows/check-binary-size.yml

@@ -5,7 +5,7 @@
 name: Check binary size
 
 on:
-  pull_request_target:
+  pull_request:
     # HACK(jubilee): something broke the distributed LLVM libso and I don't know what.
     branches: []
 #      - master