Don't hardcode the workflow name in ci.yml concurrency

https://docs.github.com/en/actions/using-jobs/using-concurrency#example-only-cancel-in-progress-jobs-or-runs-for-the-current-workflow

Author: ruohola

.github/workflows/ci.yml

@@ -6,7 +6,7 @@ on:
   pull_request:
 
 concurrency:
-  group: ci-${{ github.head_ref || github.run_id }}
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
   cancel-in-progress: true
 
 jobs: