Review test environment management

[ThomasBouche]

Description of Problem:
To test in Shapash, we install all the extra requirements and even dependencies to test machine learning model compatibility.
One problem this causes is that the tests don't match the versions of dependencies installed by pip install shapash

Potentially, the installation won't work while the tests pass.

Overview of the Solution:
The ideal solution would be to test Shapash with basic and full functionality.

We're open to different solutions