community[patch]: Correct type annotation for azure_ad_token_provider Closed: #14402 (#14432)

Description
Fix https://github.com/langchain-ai/langchain/issues/14402, Similar
changes: https://github.com/langchain-ai/langchain/pull/14166

Twitter handle
[lin_bob57617](https://twitter.com/lin_bob57617)

libs/community/langchain_community/embeddings/azure_openai.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 
 import os
 import warnings
-from typing import Dict, Optional, Union
+from typing import Callable, Dict, Optional, Union
 
 from langchain_core.pydantic_v1 import Field, root_validator
 from langchain_core.utils import get_from_dict_or_env
@@ -38,7 +38,7 @@ class AzureOpenAIEmbeddings(OpenAIEmbeddings):
         For more: 
         https://www.microsoft.com/en-us/security/business/identity-access/microsoft-entra-id.
     """  # noqa: E501
-    azure_ad_token_provider: Union[str, None] = None
+    azure_ad_token_provider: Union[Callable[[], str], None] = None
     """A function that returns an Azure Active Directory token.
 
         Will be invoked on every request.