build: add merge_group build trigger (#1900)

Needed for merge queue checks

Signed-off-by: Charlie Egan <charlie_egan@apple.com>

Author: charlieegan3

.github/workflows/build.yaml

@@ -10,6 +10,8 @@ on:
       - main
   pull_request:
   workflow_dispatch:
+  # needed for checks in merge queue
+  merge_group:
 
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