fix: deploy to china gamma accounts when PR is merged to main branch (#272)

Author: mbfreder

.github/workflows/pipeline.yaml

@@ -792,7 +792,7 @@ jobs:
         run: echo "matrix={\"include\":$(jq -r tostring .github/workflows/cn-gamma.json)}" >> $GITHUB_OUTPUT
 
   deploy-china-gamma:
-    if: ${{ github.event_name == 'release' }}
+    if: ${{ github.ref == 'refs/heads/main' || github.event_name == 'release' }}
     needs: [load-china-gamma-matrix2]
     runs-on: ubuntu-20.04
     environment: prod