[PYTHON] Update Unit Tests for LangChain updates

[ryanweiler92]

Description

Update the existing LangChan unit tests to work with the latest updates to the model class. Refer to the changes in this commit to see what was added in regards to LangChain. 9de8714

Existing

test_langchain.py

Requirements

Update the unit tests to work with the latest changes to the model class. Add any additional tests required if necessary.