ci: fix condition for release job

.github/workflows/ci.yml

@@ -159,7 +159,7 @@ jobs:
     name: Release
     runs-on: ubuntu-latest
     needs: [lint, test-typings, test-sqlite, test-postgres, test-mysql-mariadb, test-mssql]
-    if: github.event.push
+    if: github.event_name == 'push' && github.ref == 'refs/heads/v6'
     steps:
       # - uses: actions/checkout@v2
       # - uses: actions/setup-node@v1