add concurrency check to gradle-check workflow

Signed-off-by: Rishabh Singh <sngri@amazon.com>

.github/workflows/gradle-check.yml

@@ -8,6 +8,10 @@ on:
   pull_request_target:
     types: [opened, synchronize, reopened]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
 permissions:
   contents: read # to fetch code (actions/checkout)