fix(deps): update dependency litellm to v1.81.12

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
litellm	1.79.3 → 1.81.12

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[renovate]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
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The artifact failure details are included below:

File name: poetry.lock

Updating dependencies
Resolving dependencies...


Because mit-learn depends on litellm (1.81.12) which depends on openai (>=2.8.0), openai is required.
So, because mit-learn depends on openai (^1.55.3), version solving failed.