skip superfluous mvn release build steps

Author: jurgenvinju

.github/workflows/build.yaml

@@ -13,6 +13,7 @@ env:
 
 jobs:
   builds:
+    if: ${{ !(github.ref == 'refs/heads/main' && contains(github.event.head_commit.message, '[maven-release-plugin]')) }}
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2