Add concurrency control to workflow

Added concurrency configuration to ensure only one workflow runs at a time:
- Group by workflow name and git ref (branch/tag)
- Cancel in-progress runs when new push occurs
- Each branch/tag gets its own concurrency group

Behavior:
- If a build is running for main branch and you push again, the old build is cancelled
- If a build is running for main and you push a tag, tag build runs separately (different ref)
- Prevents wasted build time and resources
- Ensures latest code is always built first

Author: mtg-eagletg

.github/workflows/build-release.yml

@@ -29,6 +29,10 @@ on:
 permissions:
   contents: write
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   build:
     runs-on: windows-latest