model: mistral small 4 support (#20649)

* model: mistral small 4 support

* fix test

* fix test (2)

* Apply suggestions from code review

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* change newline

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Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>