Add concurrency guard to build workflow

Author: trask

.github/workflows/build.yml

@@ -10,6 +10,10 @@ on:
 permissions:
   contents: read
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
 jobs:
   common:
     uses: ./.github/workflows/build-common.yml