Migrate documentation to pydata sphinx theme

[Galileo-Galilei]

Description

This PR is an attempt to make doc clearer and easier to navigate thanks to the pydata-sphinx-theme

Development notes

What have you changed, and how has this been tested?

Checklist

• Read the contributing guidelines
• Open this PR as a 'Draft Pull Request' if it is work-in-progress
• Update the documentation to reflect the code changes
• Add a description of this change and add your name to the list of supporting contributions in the CHANGELOG.md file. Please respect Keep a Changelog guidelines.
• Add tests to cover your changes

Notice

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