Update license line in Python files

[UltralyticsAssistant]

This pull request updates or adds the license line to the beginning of each Python file.

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Update: Add "Ultralytics YOLOv5" to license headers throughout the repository.

📊 Key Changes

• Updated license headers across various files to explicitly mention "Ultralytics YOLOv5" instead of just "YOLOv5."

🎯 Purpose & Impact

• Clarity: Clearly attributes the YOLOv5 codebase to Ultralytics, ensuring proper credit.
• Consistency: Standardizes the license headers across the project, making it easier to identify and validate the licensing terms.
• Compliance: Ensures compliance with the AGPL-3.0 license by specifying the full project name.