Cancel concurrent workflow runs

This prevents multiple pushes from blocking up the workflow runner queue

Author: ThisIsMissEm

.github/workflows/build.yaml

@@ -1,6 +1,10 @@
 name: build
 on: [push, pull_request_target]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   test:
     runs-on: ubuntu-latest