update deepmimo tutorial to v4

[jmoraispk]

Hi Sionna Team,

This small PR updates the DeepMIMO tutorial notebook to work with DeepMIMO version 4.

Please let me know if anything is needed from our end.

Description

This PR only changed 3 code cells related to DeepMIMO and some text in the notebook. It works with the most recent version of Sionna. It introduces one considerable improvement (thanks to DeepMIMOv4): The dataset download is performed in code, allowing the notebook to be executed end-to-end without manual intervention.

Checklist

• Detailed description
• Added references to issues and discussions
• Added / modified documentation as needed
• Added / modified unit tests as needed
• Passes all tests
• Lint the code
• Performed a self review
• Ensure you Signed-off the commits. Required to accept contributions!
• Co-authored with someone? Add Co-authored-by: user@domain and ensure they signed off their commits too.

[jmoraispk]

If you're okay with it, I'd like to make one more change: to replace the image in base64, which takes up unnecessary space and pollutes diffs, with a link.

[jmoraispk]

Ready. Feel free to test the notebook in Google Colab