Fix import deprecations

[jtpio]

Fix a couple of deprecation warnings logged at JupyterLab startup:

PREFIX/envs/jupyter-ai/lib/python3.11/site-packages/langchain/_api/module_import.py:120: LangChainDeprecationWarning: Importing LLMContentHandler from langchain.llms is deprecated. Please replace deprecated imports:

>> from langchain.llms import LLMContentHandler

with new imports of:

>> from langchain_community.llms.sagemaker_endpoint import LLMContentHandler

  warn_deprecated(
PREFIX/envs/jupyter-ai/lib/python3.11/site-packages/langchain/_api/module_import.py:120: LangChainDeprecationWarning: Importing enforce_stop_tokens from langchain.llms is deprecated. Please replace deprecated imports:

>> from langchain.llms import enforce_stop_tokens

with new imports of:

>> from langchain_community.llms.utils import enforce_stop_tokens

[krassowski]

LGTM - I confirmed enforce_stop_tokens is not used and LLMContentHandler can be imported from from langchain_community.llms.sagemaker_endpoint in the lowest required version of langchain , thank you @jtpio!

[dlqqq]

Awesome work @jtpio! Thank you @krassowski for reviewing & confirming as well.