Update default GitHub assets

[glenn-jocher]

Avoid intermittent CI fails.

Signed-off-by: Glenn Jocher [email protected]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Streamlined asset naming and download process in Ultralytic's YOLOv5 GitHub repository.

📊 Key Changes

• Simplified asset list generation with a list comprehension replacing a hard-coded list of model weights.
• Removed the backup URL for downloading the assets, opting for a more straightforward download mechanism.

🎯 Purpose & Impact

• The refactoring makes adding new model sizes or types more efficient 🚀, improving code maintainability.
• By removing the backup download URL, the download process is more straightforward, which may reduce complexity and potential errors 🧹.
• Users will benefit from a cleaner and more reliable way to download necessary model files, improving user experience 🌐.