Support loading safetensors format

[gals]

By default classifiers look for pytorch_model.bin, which doesn't exist in newer versions of transformers:

pytorch_model.bin: no such file or directory

The trained model is stored using https://huggingface.co/docs/safetensors/en/index.
For example, see huggingface/transformers#28863.

[matteo-grella]

Hi @gals

We made some progresses here.

Do you have some capacity to integrate this safetensors implementation into cybertron?