Pr 3003 ci branch (#3007)

* change ChatCompletionChunk to align with "OpenAI Chat Completions streaming API"

Moving after tool_calls2

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

add in Buffering..

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

fix: handle usage outside of stream state and add tests

Simplifying everything quite a bit.

Remove the unused model_dump.

Clippy.

Clippy ?

Ruff.

Uppgrade the flake for latest transformers.

Upgrade after rebase.

Remove potential footgun.

Fix completion test.

* Clippy.

* Tweak for multi prompt.

* Ruff.

* Update the snapshot a bit.

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Co-authored-by: Nicolas Patry <patry.nicolas@protonmail.com>