ci(binaries_dev): serialize concurrent runs to prevent asset name collisions

Multiple master pushes within the same minute produced identical BUILD_TIME
values, causing concurrent workflow runs to race on identically-named release
assets. Upload retries hit 422 already_exists and failed the build. Adding a
concurrency group with cancel-in-progress ensures only the latest dev build
runs at a time, which is fine since only the latest dev artifacts matter.

.github/workflows/binaries_dev.yml

@@ -4,6 +4,10 @@ on:
   push:
     branches: [ master ]
 
+concurrency:
+  group: binaries-dev-${{ github.ref }}
+  cancel-in-progress: true
+
 permissions:
   contents: read