Update cv2.imread() patch with flags argument

[glenn-jocher]

Possible solution to #7285

🛠️ PR Summary

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🌟 Summary

Enhancement of the image reading function for better flexibility.

📊 Key Changes

• Updated the imread function definition to accept an additional argument (flags).
• Allowed users to specify image read mode by passing flags directly to the function.

🎯 Purpose & Impact

• 🛠 Purpose: To enable the customization of how images are read by providing an optional parameter. This allows developers to specify different modes like grayscale, unchanged, etc., when reading images.
• 📈 Impact to Users: Users now have more control over image processing. This can be particularly useful when working with various types of images that may require different handling (e.g., grayscale for training specific types of neural networks). It enhances the versatility of the YOLOv5 library for different image processing tasks.

[glenn-jocher]

Passes #7285 reproduction code.