Updating Dict schema to reflect current state of langchain-core (lang…

…chain-ai#311)

Co-authored-by: Leonid Kuligin <lkuligin@yandex.ru>

libs/vertexai/langchain_google_vertexai/chat_models.py

@@ -1533,15 +1533,15 @@ class AnswerWithJustification(BaseModel):
             .. code-block:: python
 
                 from langchain_core.pydantic_v1 import BaseModel
-                from langchain_core.utils.function_calling import convert_to_openai_tool
+                from langchain_core.utils.function_calling import convert_to_openai_function
                 from langchain_google_vertexai import ChatVertexAI
 
                 class AnswerWithJustification(BaseModel):
                     '''An answer to the user question along with justification for the answer.'''
                     answer: str
                     justification: str
 
-                dict_schema = convert_to_openai_tool(AnswerWithJustification)
+                dict_schema = convert_to_openai_function(AnswerWithJustification)
                 llm = ChatVertexAI(model_name="gemini-pro", temperature=0)
                 structured_llm = llm.with_structured_output(dict_schema)