GH Action Check: prevent Concurrency

Author: entorb

.github/workflows/check.yml

@@ -7,6 +7,10 @@ on:
   pull_request:
     branches: ["main"]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 permissions:
   contents: read