allow gather_for_metrics to be more flexible (#2710)
* allow gather_for_metrics to be more flexible
* style
* udapte doc
* fix
* style
* typo
* typo
* Update src/accelerate/accelerator.py
Co-authored-by: Zach Mueller <muellerzr@gmail.com>
* remove distributed
* clean
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Co-authored-by: Zach Mueller <muellerzr@gmail.com>
