removed MACE and Nequip models

[M-R-Schaefer]

The required torch versions clash / are so old that they are no longer pip installable. The nodes for the respective models have been moved to https://github.com/zincware/ips-mace https://github.com/zincware/ips-nequip

TODO:

• [ ] finish model packages
• [ ] put on pypi