CI: Cancel in-progress jobs for the same branch

Author: kateinoigakukun

.github/workflows/format.yml

@@ -5,6 +5,9 @@ on:
 jobs:
   format:
     runs-on: ubuntu-latest
+    concurrency:
+      group: ${{ github.workflow }}-${{ github.ref }}
+      cancel-in-progress: true
     container:
       image: swift:6.0.1-jammy
     steps:

.github/workflows/main.yml

@@ -5,6 +5,10 @@ on:
   push:
     branches: [main]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 jobs:
   build-macos:
     strategy: