Add favicon PNGs

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Added new favicon assets for the project.

📊 Key Changes

• 🖼️ Introduced a new favicon-yolo.png file for the YOLO branding.
• 🖼️ Added a general favicon.png file for the project.

🎯 Purpose & Impact

• 🎨 Enhances the visual identity of the project with recognizable favicon branding.
• 🌐 Improves user interface consistency, especially for browser tabs and bookmarks.

[UltralyticsAssistant]

👋 Hello @glenn-jocher, thank you for submitting an ultralytics/assets 🚀 PR! To ensure a seamless integration of your contribution, please review the checklist below:

• ✅ Define a Purpose: Clearly explain the purpose of your fix or feature in your PR description, and link to any relevant issues. Ensure your commit messages are clear, concise, and adhere to the project's conventions.
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• ✅ Update Documentation: Update the relevant documentation if needed to reflect this new or modified feature.
• ✅ Add Tests: If applicable, include or update tests to cover your changes, and confirm that all tests are passing.
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• ✅ Minimize Changes: Limit your changes to the minimum necessary for your update. "It is not daily increase but daily decrease, hack away the unessential." — Bruce Lee

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