add naive method

[aagoumbala]

Description

Adding naive method

Type of change

Please check options that are relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Tests are added in the module test_classification.py

Checklist:

• I have read the contributing guidelines
• I have updated the HISTORY.rst and AUTHORS.rst files
• Linting passes successfully : flake8 . --exclude=doc
• Typing passes successfully : mypy mapie examples --strict
• Unit tests pass successfully : pytest -vs --doctest-modules mapie
• Coverage is 100% : pytest -vs --doctest-modules --cov-branch --cov=mapie --pyargs mapie
• Documentation builds successfully : cd doc; make clean; make html