test(ci): cancel older builds

Author: akoptelov

.github/workflows/ci.yaml

@@ -5,6 +5,10 @@ on:
   pull_request:
   workflow_dispatch:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   build:
     runs-on: ubuntu-20.04