Run our GitHub actions on the merge queue (#3147)

.github/workflows/ci.yml

@@ -5,6 +5,7 @@ on:
     branches-ignore:
       - "dependabot/**"
   pull_request:
+  merge_group:
 
 concurrency:
   group: ${{ github.ref }}-${{ github.workflow }}-${{ github.event_name }}${{ github.ref == format('refs/heads/{0}', github.event.repository.default_branch) && format('-{0}', github.sha) || '' }}