Add concurrency configuration to build workflow

Agent-Logs-Url: https://github.com/angr/pypcode/sessions/1fefc66a-6a6e-4803-a0ed-d8538908cb4b

Co-authored-by: mborgerson <8210+mborgerson@users.noreply.github.com>

Author: Copilot

.github/workflows/build.yml

@@ -2,6 +2,10 @@ name: Build
 
 on: [push, pull_request]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 permissions:
   contents: read