Fix release script

Author: mhalbritter

.github/workflows/release.yml

@@ -56,7 +56,7 @@ jobs:
       version: ${{ needs.build-and-stage-release.outputs.version }}
   sync-to-maven-central:
     name: Sync to Maven Central
-    if: ${{ !COMMERCIAL }}
+    if: ${{ !vars.COMMERCIAL }}
     needs:
       - build-and-stage-release
       - verify