ci: Run only on the latest ref

Author: jcs090218

.github/workflows/test.yml

@@ -6,8 +6,12 @@ on:
   pull_request:
   workflow_dispatch:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
-  unix-test:
+  test:
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false