ci: prevent concurrent runs

Author: BoboTiG

.github/workflows/tests.yml

@@ -8,6 +8,10 @@ permissions:
   contents: write
   pull-requests: write
 
+concurrency:
+  group: ${{ github.ref }}-${{ github.workflow }}-${{ github.event_name }}-${{ github.event_name != 'pull_request' && github.sha || '' }}
+  cancel-in-progress: true
+
 jobs:
   quality:
     name: Quality