Update type to be able to use LLMMessage in a Pydantic model (#338)

Author: stellasia

src/neo4j_graphrag/types.py

@@ -16,7 +16,8 @@
 
 import warnings
 from enum import Enum
-from typing import Any, Callable, Literal, Optional, TypedDict, Union
+from typing import Any, Callable, Literal, Optional, Union
+from typing_extensions import TypedDict
 
 import neo4j
 from pydantic import (