Update stale.yml to 300 ops per run

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Improved efficiency for managing stale issues and PRs in the Ultralytics GitHub repository.

📊 Key Changes

• Increased the operations-per-run setting from 100 to 300 in the stale GitHub Action.

🎯 Purpose & Impact

• Purpose: To enhance the stale bot's capability to manage issues and PRs without hitting the rate limit too quickly.
• Impact: This will allow more issues and pull requests to be processed in a single run, reducing the time needed to mark or close stale items. It should improve repository maintenance and help in keeping the project's issues and PRs more organized and up-to-date. 🚀