Add concurrency in CI (#9855)

Author: p-r-a-v-i-n

.github/workflows/main.yml

@@ -6,6 +6,10 @@ on:
     - main
   pull_request:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   tests:
     name: Python ${{ matrix.python-version }}