Notebooks visual links update

[RizwanMunawar]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Updated image URLs for improved access and performance in notebooks.

📊 Key Changes

• Changed image URLs in heatmaps.ipynb, object_counting.ipynb, and object_tracking.ipynb to new .avif format hosted on Ultralytics servers.

🎯 Purpose & Impact

• 📈 Improved Performance: Using .avif format enhances image loading times, providing a smoother experience.
• 🔗 Reliable Access: Hosting images directly on Ultralytics ensures greater reliability and availability.
• 👥 User Experience: Clearer and faster-loading visual examples help users understand the functionalities better.

[UltralyticsAssistant]

👋 Hello @RizwanMunawar, thank you for submitting an ultralytics/notebooks 🚀 PR! This is an automated response, and an Ultralytics engineer will review your contribution soon. To help ensure a smooth integration of your updates, please check the following:

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