Fix Cohere models by using new langchain-cohere partner package

[dlqqq]

Description

• Uses new langchain_cohere partner package instead of deprecated import from langchain_community
• Uses new ChatCohere (ChatModel) class instead of deprecated Cohere (LLM) class to fix Cohere models
  • The previous Cohere class used the now-deprecated Generate endpoint.
  • The new ChatCohere class uses the Chat endpoint.

Demo

Tested with command-r language model and embed-english-v3.0 embedding model.

[jabbera]

@dlqqq new versions of langchain_cohere>1.5.0 require langchain-core >= 0.2.0 langchain-ai/langchain-cohere#52 but this project restricts it to < 0.2

jupyter-ai/packages/jupyter-ai-magics/pyproject.toml

Line 26 in 2d392b7

"langchain>=0.1.0,<0.2.0",

Any way to bump the tolerance here.