chore: skip maven publish for non-releases

.github/workflows/publish.yaml

@@ -10,6 +10,7 @@ on:
 jobs:
   publish-to-maven-central:
     runs-on: ubuntu-latest
+    if: "github.event_name == 'workflow_dispatch' || contains(github.event.head_commit.message, 'release-please--branches--main')"
     steps:
       - name: ⬇️ Checkout repository
         uses: actions/checkout@v3