MNT Remove deprecated use of load_in_8bit (#1811)
Don't pass load_in_8bit to AutoModel.from_pretrained, instead use
BitsAndBytesConfig.
There was already a PR to clean this up (#1552) but a slightly later
PR (#1518) re-added this usage.
---------
Co-authored-by: Younes Belkada <49240599+younesbelkada@users.noreply.github.com>
