Add PyTorch Hub classification CI checks

[glenn-jocher]

Add PyTorch Hub loading of official and custom trained classification models to CI checks.

May help resolve #8790 (comment)

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

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Enhanced integration with torch.hub and internal refactoring for model handling.

📊 Key Changes

• Added a code snippet to ci-testing.yml for verifying torch.hub integration.
• Renamed Model class to DetectionModel for clarity within hubconf.py.
• Updated relevant instances where Model was used to the new DetectionModel name.
• Ensured that AutoShape is only applied to instances of DetectionModel.

🎯 Purpose & Impact

• 🛠 Purpose: The update aims to improve the ease of loading YOLOv5 models directly from a local source using torch.hub and to make internal code more descriptive.
• 🚀 Impact: Users will experience more reliable model loading through code, and developers will find it easier to understand and maintain the underlying codebase.