PyTorch support documentation and examples

[andrmnl]

Hi, you mention in the readme that the package supports PyTorch models, but in ShadowModelBundle._fit you assume the model has fit method (line 116).
How exactly have you tested the PyTorch models? I was thinking of maybe using pytorch-fitmodule or SuperModule, but if there's a way you recommend already that would be great. Also it would be nice to include an example of how to load PyTorch modules in the package! (maybe I can do a PR after I'm able to do it myself :-)

[bogdan-kulynych]

Hi, ShadowModelBundle and AttackModelBundle take a scikit-like object, with fit, predict, and predict_proba methods. You can use skorch to wrap your torch model in such an API, or mia's own mia.wrappers.TorchWrapper. You can see example tests that use skorch (shadow, attack, serializers).

[bogdan-kulynych]

If you can add an example, that would be great!

[andrmnl]

Ah great I haven't seen the TorchWrapper! In the end I just wrote my own class, but indeed using skorch should be better, I'll do that instead, thanks.