[Bug]: Adapt to MistralAI version migration

### What happened?

Hi!

I have opened a pull request 3 months ago, but there had been no activity on it, so I open this issue.

MistralAI has deployed the version 2.0.0 of its python package on March 10th, introducing a change in its structure. One of the main changes is the switch `from mistralai import Mistral` to `from mistralai.client import Mistral`.

However, in [`chromadb/utils/embedding_functions/mistral_embedding_function.py`](https://github.com/chroma-core/chroma/blob/main/chromadb/utils/embedding_functions/mistral_embedding_function.py#L22), you make a check on MistralAI Python package by doing `from mistralai import Mistral`. This import/check does not work with Mistral python package v2.

My [PR ](https://github.com/chroma-core/chroma/pull/7105) contains a suggestion on how to handle it. However, it might not be the cleanest implementation.

### Versions

Chroma v1.5.9, Python 3.11.13

### Relevant log output

```shell

```

Start in chromadb/utils/embedding_functions/mistral_embedding_function.py and compare the proposed approach in PR #7105 with the MistralAI v2 import change described here. Confirm the dependency check recognizes the supported package structure and that the embedding function retains existing behavior.

Written by the indexing model from the issue text.