Update stale.yml

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Workflow optimization for handling stale issues and PRs 🔄.

📊 Key Changes

• Changed the number of days before marking issues/PRs as stale from 60 to 30.
• Unchanged the number of days before closing stale issues/PRs, which remains at 5.

🎯 Purpose & Impact

• The change aims to streamline the project's maintenance by addressing issues and pull requests more quickly, potentially reducing the clutter of inactive discussions.
• The impact for users includes a need to respond more promptly to bot notifications to prevent automatic marking/closing of their contributions as stale. ✅