Fix release workflow permissions for creating releases

Added 'contents: write' permission to allow GITHUB_TOKEN to create
releases. This fixes the 403 error when the workflow tries to create
a GitHub release.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.github/workflows/release.yml

@@ -5,6 +5,9 @@ on:
     tags:
       - 'v*.*.*'
 
+permissions:
+  contents: write
+
 env:
   CARGO_TERM_COLOR: always
   RUST_BACKTRACE: 1