automatically cancel superseded ci build of pr

.github/workflows/build.yml

@@ -12,6 +12,10 @@ on:
   check_suite:
     types: [rerequested]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 jobs:
   test:
     runs-on: ubuntu-20.04

.github/workflows/ports_windows.yml

@@ -12,6 +12,10 @@ on:
       - 'ports/unix/**'
       - 'ports/windows/**'
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 jobs:
   build:
     runs-on: windows-2019

.github/workflows/pre-commit.yml

@@ -8,6 +8,10 @@ on:
   pull_request:
   push:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 jobs:
   pre-commit:
     runs-on: ubuntu-20.04