Add project: apax: Atomistic learned Potentials in JAX!

[PythonFZ]

What kind of change does this PR introduce?

• Add a project
• Update a project
• Remove a project
• Add or update a category
• Change configuration
• Documentation
• Other, please describe:

Description:
apax is a high-performance, extendable package for training of and inference with atomistic neural networks.
It implements the Gaussian Moment Neural Network model [2, 3].
It is based on JAX and uses JaxMD as a molecular dynamics engine.

Checklist:

• I have read the CONTRIBUTING guidelines.
• I have not modified the README.md file. Projects are only supposed to be added or updated within the projects.yaml file since the README.md file is automatically generated.

[Irratzo]

Thanks for the addition @PythonFZ! I will add you as co-author with your ORCiD in the next release, see #256. This month, hopefully.

[Irratzo]

@PythonFZ, I added you to CITATION.cff. Hope that's okay, and thanks again.