Add concurrency for ci-snapshot.yml to support branches

**Auto-cherry-pick to `6.1.x`**

Author: artembilan

.github/workflows/ci-snapshot.yml

@@ -8,6 +8,10 @@ on:
       - main
       - '*.x'
 
+concurrency:
+  group: group-snapshot-for-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   build-snapshot:
     uses: spring-io/spring-github-workflows/.github/workflows/spring-artifactory-gradle-snapshot.yml@main