Add hubconf.py argparser

[glenn-jocher]

Usage:

python hubconf.py --model yolov5n

Bonus: eliminates yolov5s downloads during CI, only yolov5n

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Enhancement of model selection flexibility in CI testing and inference script.

📊 Key Changes

• Added an argument parser in hubconf.py to allow model selection via command-line argument.
• Updated GitHub Actions CI workflow to use a model variable when calling hubconf.py.

🎯 Purpose & Impact

• 🎛 Provides developers with easier ways to specify which model to test, improving the developer experience.
• 🔧 Simplifies integration and continuous testing for different models, enhancing overall codebase reliability.
• ✅ Allows users to quickly test different models, potentially boosting productivity and facilitating experimentation.