🎨 style(MentionItem): update hover color

[berry-13]

Summary

fix #2668

Change Type

• [x] Bug fix (non-breaking change which fixes an issue)

Checklist

• [x] My code adheres to this project's style guidelines
• [x] I have performed a self-review of my own code
• [x] I have commented in any complex areas of my code
• [x] I have made pertinent documentation changes
• [x] My changes do not introduce new warnings
• [x] I have written tests demonstrating that my changes are effective or that my feature works
• [x] Local unit tests pass with my changes
• [x] Any changes dependent on mine have been merged and published in downstream modules.
• [x] New documents have been locally validated with mkdocs