Use pydantic 2 with v1 sub-package.

[tibuch]

Hi,

Thank you for the amazing pre-trained models and all the work you put into making them easily available!

I was hoping that we can simply bump pydantic to version 2 and use pydantic.v1 inside go-nuclear. This would allow me to make use of pydantic2 features in my own config files :nerd_face:

Note: I did not run any tests with this change.

What do you think?

Cheers