Modify to support batch size N

[quinle]

Hi,
Thank you so much for the great project, it is amazing. This PR is for adding support for OPT inference batch size N.
I'm looking forward to your review ^^

[yxuansu]

Hi @quinle -- Thank you for your interest in our work and the great effort! We will take a closer look to your commits, many thanks!

@gmftbyGMFTBY Are you able to review the PR by any chance?

[yxuansu]

Hi @quinle -- Thank you again for your interest in our work. We are glad that Huggingface has officially supported contrastive search in transformers. Here, we provide a short tutorial. In transformers, contrastive search supports batch inference by default.

Hope this resource could help you :-)

Best,

Yixuan