fix: resolve Pydantic test error and import sorting

Author: RN

libs/community/langchain_community/chat_models/mlx.py

@@ -4,7 +4,6 @@
 import logging
 import re
 import uuid
-
 from typing import (
     Any,
     Callable,

libs/community/tests/unit_tests/chat_models/test_mlx.py

@@ -36,6 +36,7 @@ class _FakeLLM(MLXPipeline):
     pipeline_kwargs: dict = {}
 
     def __init__(self) -> None:
+        super().__init__()
         self.tokenizer = _FakeTokenizer()
 
     def _generate(self, prompts, stop=None, run_manager=None, **kwargs):