Add GHA CI autocancel (#208)

Author: trsvchn

.github/workflows/ci.yml

@@ -7,6 +7,11 @@ on:
  schedule:
  - cron: '0 0 * * *'
 
+concurrency:
+ # <workflow_name>-<branch_name>-<true || commit_sha (if branch is protected)>
+ group: ci-${{ github.ref_name }}-${{ !(github.ref_protected) || github.sha }}
+ cancel-in-progress: true
+
 jobs:
  tests:
  runs-on: ${{ matrix.os }}