Update build.yml

Author: timkpaine

.github/workflows/build.yml

@@ -9,6 +9,10 @@ on:
     # run on sunday nights
     - cron:  '0 0 * * 0'
 
+concurrency:
+   group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+   cancel-in-progress: true
+
 jobs:
   build:
     runs-on: ubuntu-latest