Limit concurrency of GitHub workflow for CI runs

Author: diemogebhardt

.github/workflows/ci.yml

@@ -10,6 +10,10 @@ on:
 permissions:
   contents: read
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 jobs:
   test:
     name: test