Update links.yml

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Updated the link checker GitHub workflow to include a custom User-Agent header.

📊 Key Changes

• Added a User-Agent header string to the link checker configuration in the .github/workflows/links.yml file.

🎯 Purpose & Impact

• Purpose: This change aims to ensure that the link checker tool mimics a legitimate browser request, potentially reducing false positives when checking links.
• Impact: Users will benefit from more accurate link validation in project documentation, reducing the likelihood of mistakenly marked broken links. This makes continuous integration smoother and more reliable. 🌐✅