Fix security: Add explicit permissions to changeset-check workflow

- Add contents: read permission to changeset-check.yml
- Addresses CodeQL security recommendation for workflow permissions

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

.github/workflows/changeset-check.yml

@@ -4,6 +4,9 @@ on:
   pull_request:
     types: [opened, synchronize, reopened, labeled, unlabeled]
 
+permissions:
+  contents: read
+
 jobs:
   check:
     name: Check for Changeset