Make test-notebooks job cancelable

Author: mdpiper

.github/workflows/test-notebooks.yml

@@ -2,13 +2,15 @@ name: Test Notebooks
 
 on: [push, pull_request]
 
-jobs:
+concurrency:
+  group: ${{ github.ref }}-${{ github.workflow }}
+  cancel-in-progress: true
 
+jobs:
   test-notebooks:
 
     if:
-      github.event_name == 'push' ||
-      github.event.pull_request.head.repo.full_name != github.repository
+      github.event_name == 'push' || github.event.pull_request.head.repo.full_name != github.repository
 
     name: Test the notebooks
     runs-on: ubuntu-latest