Cancel any tests running when a new commit is pushed.

Author: neogeek

.github/workflows/test.workflow.yml

@@ -9,6 +9,10 @@ on:
     branches:
       - main
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   tests:
     runs-on: ${{ matrix.os }}