feat: integration Mistral V1.0 support

[tcapelle]

This adds support for the newly released Mistral v1.0 SDK: https://github.com/mistralai/client-python/blob/main/MIGRATION.md

• Moves mistralai<1.0 to v0 and adds support for +v1.0 in the folder v1.
• I also changed the logic on the accumulator to return a CompletionChunk instead of a CompletionResponse (similar to OpenAI)

[circle-job-mirror[bot]]

Preview this PR with FeatureBee: https://beta.wandb.ai/?betaVersion=e2cd5566b90e2c7812f8945f4bfda7487520fcad

[tcapelle]

I have failing tests outside of my scope:

[andrewtruong]

I have failing tests outside of my scope:

I don't see this -- maybe just your env?

[tcapelle]