feat(ci): add concurrency to test workflow

Enhance the GitHub Actions test workflow by adding concurrency 
settings.

.github/workflows/tests.yml

@@ -1,6 +1,10 @@
 name: tests
 on: [pull_request]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   tests:
     runs-on: ubuntu-latest