FIX: Fix 8-bit serialization tests (#30051)
* fix 8-bit serialization tests
* add more clarification
* Update src/transformers/quantizers/quantizer_bnb_8bit.py
Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
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Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
