test(ci): switch to use pull_request_target (#644)

Author: christinewangcw

.github/workflows/test.yml

@@ -4,7 +4,7 @@ on:
   push:
     branches:
       - "develop"
-  pull_request:
+  pull_request_target:
     types: [ opened, synchronize, reopened, labeled ]
     branches:
       - "develop"