Default to `gpt-4o` model

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Updated the default OpenAI model used in the codebase.

📊 Key Changes

• Changed the default OpenAI model from gpt-4o-2024-05-13 to gpt-4o in several files.

🎯 Purpose & Impact

• Simplification: Streamlines the model selection by using a more general default, reducing the need for frequent updates.
• Flexibility: Allows for easier alignment with current OpenAI models without specifics that may lead to deprecation.
• User Benefit: Minimizes potential disruptions caused by model updates, ensuring smoother operation. 🚀