Serialize release workflow to prevent major-tag race conditions (#1266)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: Copilot

.github/workflows/release.yml

@@ -22,6 +22,13 @@ on:
 permissions:
   contents: write
 
+# Serialize all release runs to prevent race conditions when force-updating major version tags.
+# Without this, concurrent releases could race on updating the same floating major tag (e.g., v0).
+# cancel-in-progress: false ensures each release completes rather than being cancelled.
+concurrency:
+  group: release
+  cancel-in-progress: false
+
 jobs:
   release:
     runs-on: ubuntu-latest