ci: add workflow concurrency (#96)

Author: ReenigneArcher

.github/workflows/ci.yml

@@ -6,10 +6,19 @@ name: CI
 
 on:
   pull_request:
-    branches: [master]
-    types: [opened, synchronize, reopened]
+    branches:
+      - master
+    types:
+      - opened
+      - synchronize
+      - reopened
   push:
-    branches: [master]
+    branches:
+      - master
+
+concurrency:
+  group: "${{ github.workflow }}-${{ github.ref }}"
+  cancel-in-progress: true
 
 jobs:
   setup_release: