[ci] Allow early abort of the jobs if somebody pushed to the same PR.

Author: vgvassilev

.github/workflows/main.yml

@@ -9,6 +9,10 @@ on:
     branches:
     - main
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
 jobs:
   unix: