Add the ref

Change-Id: I1fd3eb6ed0158a80511bc75d315d99d8650f5a6e

.github/workflows/Build.yaml

@@ -40,6 +40,7 @@ jobs:
         with:
           commit_message: Apply Spotless
           repository: ${{ github.event.pull_request.head.repo.full_name }}
+          ref: ${{ github.head_ref }}
 
       - name: Build all build type and flavor permutations
         run: ./gradlew assemble