Update plots.py

[glenn-jocher]

🛠️ PR Summary

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🌟 Summary

Improved visualization range in validation study plots.

📊 Key Changes

• Expanded the model set included in the plot generation from yolov5s6, yolov5m6, yolov5l6, yolov5x6 to include yolov5n6.
• Adjusted the lower limit of the y-axis in the plot from 30 to 25 for better data representation.

🎯 Purpose & Impact

• Purpose: To enhance the plotting functionality in the validation study by including additional models and adjusting the visualization scale.
• Impact: Users can now see a broader range of models when visualizing performance, and the plots can display a wider spectrum of validation results, potentially offering a more comprehensive view of smaller performance increments.