Remove formats variable to avoid pd conflict

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Improved clarity and fixed export conditions in yolov5 model exporting and benchmark utilities.

📊 Key Changes

• Renamed variable formats to fmts for better readability in export.py.
• Modified conditional checks for half-precision (FP16) model conversions to be more explicit.
• Adjusted assertions to prevent simultaneous TFLite and TF.js export, ensuring users export one format at a time.
• Streamlined formats logic in benchmarking by calling export.export_formats() directly within loop iterations.

🎯 Purpose & Impact

• 🚀 The renaming of the variable improves code maintainability and understandability.
• 🛠️ More explicit conditionals reduce the potential for conversion errors when exporting models in different precision modes.
• ⛔️ Explicit assertions guide users to avoid incorrect usage scenarios, such as trying to export incompatible formats together, enhancing user experience and preventing confusion.
• 🧹 Inlining export.export_formats() calls simplifies the code and may slightly improve performance in benchmarks by reducing redundancy.

Overall, these changes contribute to a cleaner and more user-friendly codebase with better guidance on model exporting procedures.

[glenn-jocher]

@sazzadhrz this PR is unrelated to PyTorch HUB.

If you have a reproducible bug please submit a full bug report with exact code to reproduce, thank you!