Support Pydantic models in server endpoint args and return type

[ddayan]

Support any pydentic based models in endpoint arguments and return type:

class Message(BaseModel):
....

class Response(BaseModel):
....

Expected behaviour fails:

  @endpoint
    def generate(self, request: Message) -> Response:
        embedding = self.tokenizer.embedding_function.encode(request.content)
        return Response(embedding) 

Workaround:

   @endpoint
    def generate(self, request: Message) -> dict:
        request = Message.model_validate(request)
        embedding = self.tokenizer.embedding_function.encode(request.content)
        return {"response": embedding}