Unpin einx<0.4.0 constraint in pyproject.toml, which will require migrating to community Boltz fork

[k-chrispens]

This repo removes the strict pins, and also has some nice QOL improvements over the seemingly unmaintained Boltz repo. https://github.com/Novel-Therapeutics/boltz-community

[k-chrispens]

Will also require changing all einx.rearrange to einx.id and all einx.vmap to einx.torch/jax.adapt_with_vmap https://einx.readthedocs.io/en/latest/api/adapters/torch/einx.torch.adapt_with_vmap.html

[k-chrispens]

#316 will be resolved more fully by this. Given that the weights are the same and the deps are relaxed a lot, I think it would be worth swapping over. @marcuscollins advise on priority here?

[k-chrispens]

And #276