Bump minimum langchain version so that a Marvin upgrade works if existing langchain is <0.0.200

[discdiver]

First check

• I added a descriptive title to this issue.
• I used the GitHub search to try to find a similar issue and didn't find one.
• I searched the Marvin documentation for this issue.

Bug summary

@zzstoatzz pointed me toward updating my langchain version and that resolved the issue

I searched through langchain's history and found that the issue was introduced in 0.0.200 (3 days ago). The commit in question: langchain-ai/langchain#6113

I'll update the minimum langchain version in pyproject.toml.

Reproduction

With an old (<0.0.200) version of langchain installed
I did pip install -U marvin
then marvin chat

Error

Traceback (most recent call last):
  File "/Users/jeffhale/miniforge3/bin/marvin", line 5, in <module>
    from marvin.cli.cli import app
  File "/Users/jeffhale/miniforge3/lib/python3.10/site-packages/marvin/__init__.py", line 28, in <module>
    from marvin.ai_models import ai_model
  File "/Users/jeffhale/miniforge3/lib/python3.10/site-packages/marvin/ai_models/__init__.py", line 1, in <module>
    from .base import ai_model, AIModel
  File "/Users/jeffhale/miniforge3/lib/python3.10/site-packages/marvin/ai_models/base.py", line 14, in <module>
    from marvin.utilities.llms import call_llm_messages, get_model
  File "/Users/jeffhale/miniforge3/lib/python3.10/site-packages/marvin/utilities/llms.py", line 6, in <module>
    from langchain.schema import AIMessage, FunctionMessage, HumanMessage, SystemMessage
ImportError: cannot import name 'FunctionMessage' from 'langchain.schema' (/Users/jeffhale/miniforge3/lib/python3.10/site-packages/langchain/schema.py)

Versions

0.10.0

Additional context

No response