ci: Use GitHub concurrency

.github/workflows/cygwin.yml

@@ -1,5 +1,9 @@
 name: cygwin
 
+concurrency:
+  group: cygwin-${{ github.head_ref }}
+  cancel-in-progress: true
+
 on:
   push:
     paths:

.github/workflows/file_format.yml

@@ -2,6 +2,10 @@ name: File format check
 
 on: [push, pull_request]
 
+concurrency:
+  group: file_fmt-${{ github.head_ref }}
+  cancel-in-progress: true
+
 jobs:
   format:
     runs-on: ubuntu-latest

.github/workflows/images.yml

@@ -1,5 +1,9 @@
 name: CI image builder
 
+concurrency:
+  group: img_builder-${{ github.head_ref }}
+  cancel-in-progress: true
+
 on:
   push:
     branches:

.github/workflows/lint_mypy.yml

@@ -1,5 +1,9 @@
 name: LintMypy
 
+concurrency:
+  group: mypy-${{ github.head_ref }}
+  cancel-in-progress: true
+
 on:
   push:
     paths:

.github/workflows/macos.yml

@@ -1,5 +1,9 @@
 name: macos
 
+concurrency:
+  group: macos-${{ github.head_ref }}
+  cancel-in-progress: true
+
 on:
   push:
     paths:

.github/workflows/msys2.yml

@@ -1,5 +1,9 @@
 name: msys2
 
+concurrency:
+  group: msys2-${{ github.head_ref }}
+  cancel-in-progress: true
+
 on:
   push:
     paths:

.github/workflows/nonative.yml

@@ -1,5 +1,9 @@
 name: Cross-only compilation environment
 
+concurrency:
+  group: nonative-${{ github.head_ref }}
+  cancel-in-progress: true
+
 on:
   push:
     branches:

.github/workflows/os_comp.yml

@@ -1,5 +1,9 @@
 name: linux
 
+concurrency:
+  group: linux-${{ github.head_ref }}
+  cancel-in-progress: true
+
 on:
   push:
     branches:

.github/workflows/unusedargs_missingreturn.yml

@@ -9,6 +9,10 @@ env:
   CPPFLAGS: "-Werror=unused-parameter -Werror=return-type"
   FFLAGS: "-fimplicit-none"
 
+concurrency:
+  group: unusedargs-${{ github.head_ref }}
+  cancel-in-progress: true
+
 on:
   push:
     paths:

.github/workflows/website.yml

@@ -1,5 +1,10 @@
 name: Update website
 
+concurrency:
+  group: mesonbuild.com
+  # We do NOT want `cancel-in-progress` here since only one website job
+  # should run at a time to avoid upload race condtions.
+
 on:
   push:
     branches: