Add concurrency control to unit test workflow

Co-authored-by: jpayne3506 <[email protected]>

Author: Copilot

.github/workflows/unit-tests.yaml

@@ -10,6 +10,9 @@ on:
   merge_group:
     types:
       - checks_requested
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 jobs:
   unit-tests:
     strategy: