chore: add GitHub concurrency

Author: vincentchalamon

.github/workflows/ci.yml

@@ -4,6 +4,10 @@ on:
   push:
   pull_request:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 env:
   COVERAGE: '0'