ci: cancel in-progress runs when new runs start (concurrency)

Author: yangchenlarkin

.github/workflows/ci.yml

@@ -6,6 +6,10 @@ on:
   pull_request:
     branches: [ main ]
 
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   test:
     name: Test