Merge pull request #488 from jasoncouture/concurrency_limit

Only allow one build in parallel per ref

.github/workflows/main.yml

@@ -4,6 +4,9 @@ on:
     branches: [master]
   pull_request:
     branches: [master]
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 jobs:
   build: