ci: concurrency with cancel-in-progress false (#237)

Author: gadomski

.github/workflows/ci.yaml

@@ -6,6 +6,10 @@ on:
       - main
   pull_request:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: false
+
 jobs:
   ci:
     name: CI