Fix staleness test workflow

PiperOrigin-RevId: 537256933

.github/workflows/staleness_check.yml

@@ -17,14 +17,15 @@ jobs:
 
     name: Test staleness ${{ matrix.os.name }} ${{ matrix.branch}}
     runs-on: ${{ matrix.os.value }}
-    if: ${{ github.event.repository.full_name == 'protocolbuffers/protobuf' || matrix.branch == 'main '}}
     steps:
       - name: Checkout ${{ matrix.branch }}
+        if: ${{ github.event.repository.full_name == 'protocolbuffers/protobuf' || matrix.branch == 'main '}}
         uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
         with:
           ref: ${{ matrix.branch}}
 
       - name: Run all staleness tests
+        if: ${{ github.event.repository.full_name == 'protocolbuffers/protobuf' || matrix.branch == 'main '}}
         uses: protocolbuffers/protobuf-ci/bazel@v1
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}