Add concurrency cancellation to GHA workflows.

Author: cboulay

.github/workflows/cppcmake.yml

@@ -19,11 +19,14 @@ on:
         required: false
         default: ''
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 defaults:
   run:
     shell: bash
 
-
 jobs:
   build:
     name: ${{ matrix.config.name }}

.github/workflows/mingw_static.yml

@@ -10,6 +10,10 @@ on:
       - '.github/workflows/mingw_static.yml'
   pull_request:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 jobs:
   build:
     name: MinGW batteries-included