Fix `jax.config`, remove astropy import

[dgegen]

Two small changes to ensure that nuance runs without errors after installation via pip.

• from jax.config import config raises an ImportError in the newest version of JAX (0.4.25). It turns out that importing the jax.config submodule via import jax.config is deprecated and referencing the config object via jax.config is encouraged. Thus, config = jax.config was added to __init__.py, so that nuance.config can still be used to access jax.config as was the case previously, although one could probably debate whether this is desirable conceptually.
• star.py imports import astropy.units as u, but astropy was not listed as a dependency in pyproject.toml.

Keep up the inspiring work!

[lgrcia]

Hi @dgegen and thanks for the changes, both relevant. astropy is imported but astropy.units is actually not used. That's intentional, to avoid having it as a dependency. Could you remove the import and keep astropy out of the dependencies? Otherwise good catch on the new jax version.

[dgegen]

Thanks!

Regarding astropy: I'm afraid I've run into problems without adding astropy as an additional dependency: If I install Nuance from GitHub into a fresh environment and then only change the jax.config lines in the __init__.py file, I face the following error:

>>> import nuance
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/usr/pydev/nuance/nuance/nuance/__init__.py", line 11, in <module>
    from nuance.star import Star
  File "/Users/usr/pydev/nuance/nuance/nuance/star.py", line 3, in <module>
    import astropy.units as u
ModuleNotFoundError: No module named 'astropy'

[lgrcia]

Sure, it makes sense since it is imported in this file. Unless I am missing something I think you can remove the import in star.py (https://github.com/lgrcia/nuance/blob/main/nuance/star.py#L3)

[dgegen]

Oh my – I am being silly again! For some reason I had thought you just wanted me to take out the dependency, but re-reading it now, I see that you clearly said to take out the import as well 🙈 Sorry for the inconvenience – writing your last message must have been a bit disturbing :))

[lgrcia]

No worries at all :) Thanks a lot for these additions!

[lgrcia]

Oh one last thing before merging. Can you bump the minor version of the package in the pyproject file? It should be 0.6.1 now I think.

[dgegen]

Done!