nucleus -inf overflow (#2470)
nucleus -inf overflow (#2470)

* nucleus -inf overflow

* black

* undo move of eos penalty

* convert scores to fp32 before search instead of manually clamping results

Co-authored-by: Spencer Poff <436fd2467f933ea671cb058fd2147aec370125bd@fb.com>
facebookresearch/ParlAI,facebookresearch/ParlAI,facebookresearch/ParlAI,facebookresearch/ParlAI,facebookresearch/ParlAI