FIX: Remove pandas in package import

[thibaultcordier]

Description

Error importing MapieTimeSeriesRegressor because pandas is not a required package in mapie. It is therefore proposed that this unnecessary dependency be removed and that only numpy arrays be managed.

Fixes #395

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• [x] Import MapieTimeSeriesRegressor without pandas requirement.

Checklist

• [x] I have read the contributing guidelines
• [x] I have updated the HISTORY.rst and AUTHORS.rst files
• [x] Linting passes successfully : make lint
• [x] Typing passes successfully : make type-check
• [x] Unit tests pass successfully : make tests
• [x] Coverage is 100% : make coverage
• [x] Documentation builds successfully : make doc