Cohere can specify models

[yhfgyyf]

Fixed the bug where “from langchain_cohere.llms import Cohere”，Cohere could not specify models.

[Anirudh31415926535]

Hi @yhfgyyf Thanks so much for the PR!
Just so that I understand better, could you maybe provide an example code snippet that works now after this PR, but not before?
Also, please do add a unit test for this change in /libs/cohere/tests/unit_tests/test_llm.py.

[yhfgyyf]

from langchain_cohere.llms import Cohere llm = Cohere(model="command",cohere_api_key=cohere_key,temperature=0) llm.invoke("hello")
fix the issue #44

[Anirudh31415926535]

@yhfgyyf Hi, got it, the fix looks good! Could you please just add the unit test in? We can merge it after that!