FEAT [`Trainer` / `bnb`]: Add RMSProp from `bitsandbytes` to HF `Trainer` (#29082)
* add RMSProp to Trainer
* revert some change
* Update src/transformers/trainer.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>