Add concurrency settings to unit tests workflow

.github/workflows/unit-tests.yml

@@ -7,6 +7,10 @@ on:
   pull_request:
     branches: [ main ]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   tests:
     name: Run unit tests