CI: Add types to automerge.yml (#100066)

* Add `types` to automerge.yml 

from https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request we need to specify our `types`

* Update automerge.yml

no quotes

* Update .github/workflows/automerge.yml

.github/workflows/automerge.yml

@@ -1,6 +1,8 @@
 name: AutoMerge
 on:
   pull_request:
+    # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request
+    types: [opened, reopened, labeled, synchronize]
   schedule:
     # The cron job is just a fallback.
     # The "stopwatch" functionality that we have implemented should