Add retry=3 to download()

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Enhancements to dataset download process with improved error handling and optional cURL utility.

📊 Key Changes

• The download function now accepts a retry parameter for multiple download attempts.
• cURL can be optionally used in dataset downloading by setting the curl parameter to True.
• Download error handling has been improved with retries and warnings on failure.

🎯 Purpose & Impact

• 🔄 The introduction of the retry mechanism aims to make downloading more robust, especially in unreliable network conditions.
• 🚀 Using cURL as an alternate download method provides flexibility and may improve download speeds or reliability for some users.
• ⚠️ Better error messages on download failures will help users diagnose and rectify issues more effectively, improving the overall user experience.