Add workflow concurrency

Author: DOKOS-TAYOS

.github/workflows/ci.yml

@@ -9,6 +9,10 @@ on:
 permissions:
   contents: read
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   smoke-minimal:
     runs-on: ubuntu-latest