Remove setting of the _root_ logger level as this is best done by the…

[erwinscholtens]

As I understand it: The root logger should not be changed by a library. The reason for this is that now anyone using Mistral Client will have their root logger changed and log statements in the calling code will be affected (both by the level and the formatting). This behavior can be seen by the following snippet:

import logging

# from mistralai.client import MistralClient

logger = logging.getLogger(__name__)
logger.warning("hi")

The logger warning will only be displayed if the second line is commented, because otherwise the log level will be set to ERROR.

The suggested solution is to leave the formatting and level to the end user (calling code) and remove it from here.

[fuegoio]

Thank you for your contribution your are right :)