Update default.yml

Author: mfranzke

.github/workflows/default.yml

@@ -7,6 +7,10 @@ on:
     branches:
       - "main"
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
+
 jobs:
   build-examples:
     name: Build example