schedulefree optimizers (#30079)
* schedulefree optimizers
* fix train instead of eval for optimizer
* fixes and update docs
* chore: lint
* add tests and drop overly-verbose _32bit suffix
* chore: lint
* fix for docs
* fix code review issues
* use duck-typing to avoid per-optimizer patches
* fixup style
* fixup style
* warn if incorrect accelerate version with schedule free
Co-authored-by: Aman Gupta Karmani <aman@tmm1.net>
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Co-authored-by: Aman Karmani <aman@tmm1.net>
