Remove redundant targets for pr_target

Author: alextwoods

.github/workflows/pull-request-build.yml

@@ -2,7 +2,6 @@ name: Build SDK
 on:
   merge_group:
   pull_request_target:
-    types: [opened, synchronize, reopened]
 
 concurrency:
   group: start-pull-request-build-${{ github.event.pull_request.number || github.ref }}