Fix condition for snapshot releases in maven CI action (#999)

.github/workflows/maven.yml

@@ -28,7 +28,7 @@ jobs:
       # Make github release
     - name: Release
       uses: softprops/action-gh-release@v2
-      if: ${{ github.ref_name == 'main' && github.event.pull_request.merged == true}} # only make snapshot release if it is a push to main
+      if: ${{ github.event.pull_request.base.ref == 'main' && github.event.action == 'closed' && github.event.pull_request.merged == true}} # only make snapshot release if it is a push to main
       with:
         name: Latest snapshot release
         tag_name: snapshot