MAINT: Bump litellm from 1.83.0 to 1.84.0 in the security-minor-and-patch group across 1 directory

[dependabot]

Bumps the security-minor-and-patch group with 1 update in the / directory: litellm.

Updates litellm from 1.83.0 to 1.84.0

Commits

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[Roman Lutz (romanlutz)]

The pipelines are failing for two separate reasons:

1. LiteLLM 1.84.0 adds openai>=2.20.0,<3.0.0. Combined with PyRIT's openai>=2.2.0 requirement, uv resolves OpenAI 2.54.0 instead of 3.1.0. The ty pre-commit check then fails because five # ty: ignore[deprecated] comments in openai_video_target.py are no longer needed with OpenAI 2. Removing those suppressions should fix this check.
2. The coverage failure is unrelated to this dependency update. The branch is behind main, so diff coverage includes newer changes to odin_dataset.py and promptintel_dataset.py and reports 68%, below the 90% threshold. Merging current main should fix that comparison.

LiteLLM continues to require openai<3.0.0 in every published release through the current 1.97.0, so upgrading LiteLLM further will not avoid the OpenAI downgrade.