Problems with destructor.

[vyastreb]

There's a problem when the Mistral client is deleted.

Minimal example:

from mistralai.client import MistralClient
from mistralai.models.chat_completion import ChatMessage
import os
# Retrieve API key
try:
    api_key = os.environ["MISTRAL_API_KEY"]
except KeyError:
    print("Error: MISTRAL_API_KEY environment variable is not set.")
    exit()

client = MistralClient(api_key=api_key)

chat_response = client.chat(
    model="mistral-tiny",
    messages=[ChatMessage(role="user", content="How many fingers do you have?")],
    temperature=0.5, 
    max_tokens=10,
)
bot_response = chat_response.choices[0].message.content
print(bot_response)

Output

$ python3.10 minimalExample.py 
I don't have fingers, I'm
Exception ignored in: <function MistralClient.__del__ at 0x7f79bf7439a0>
Traceback (most recent call last):
  File ~/.local/lib/python3.10/site-packages/mistralai/client.py", line 49, in __del__
  File ~/.local/lib/python3.10/site-packages/httpx/_client.py", line 1272, in close
  File ~/.local/lib/python3.10/site-packages/httpx/_transports/default.py", line 243, in close
  File ~/.local/lib/python3.10/site-packages/httpcore/_sync/connection_pool.py", line 324, in close
  File ~/.local/lib/python3.10/site-packages/httpcore/_sync/connection.py", line 172, in close
TypeError: 'NoneType' object is not callable

Solution suggestions: in ./mistralai/client.py.
A temporary solution, e.g. replace

    def __del__(self) -> None:
        self._client.close()

by

    def __del__(self) -> None:
        if self._client and getattr(self._client, 'close', None):
            try:
                self._client.close()
            except Exception as e:
                pass