Auto cancel stale GH workflows (#398)

Author: devhawk

.github/workflows/on_pr.yml

@@ -11,6 +11,10 @@ on:
       - reopened
       - synchronize
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   test:
     uses: ./.github/workflows/test.yml