Description

This PR is the first part of a duet to address the issue #520.
Formatting, using black, have been applied on all files but the notebooks, introducing quite a lot of changes.

Linting, using flake8, will come in a separate PR so the modifications are not hidden by the formatting changes.

Fixes #520 (partially)

Type of change

Please delete options that are not relevant.

• Global code formatting upgrade

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Run all tests succesfully.

Note : i had to upgrade shap to 0.44 to make the tests pass. 0.41 was throwing an error despite the fact that the minimum requirements is 0.38.1

Test Configuration:

• OS: CentOs
• Python version: 3.10.8
• Shapash version: 2.4.1

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules