try null environment

Author: alvicsam

.github/workflows/ci.yml

@@ -41,7 +41,7 @@ jobs:
   docker-build:
     runs-on: ubuntu-latest
     timeout-minutes: 10
-    environment: prod
+    environment: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' && 'prod' || null }}
     needs: [set-variables]
     strategy:
       fail-fast: false