Fix CI

[landreman]

The CI appears to be broken. For the extensive tests with python 3.10 and 3.11 but not 3.9, there is a failure early on when pyoculus is installed.

This PR doesn't yet have a fix, just documenting that the problem occurs even for the master branch.

[landreman]

The error appears to be related to f2py:

    File "/tmp/pip-build-env-78kkn94r/overlay/lib/python3.11/site-packages/numpy/f2py/capi_maps.py", line 377, in getpydocsign
      sig = '%s : %s %s%s' % (a, opt, c2py_map[ctype], init)
                                      ~~~~~~~~^^^^^^^
  KeyError: 'void'

I seem to remember this error appearing in the simsopt CI also last summer when numpy v2 was released, but I'm not certain. @smiet @mbkumar any ideas how to fix this?

[mbkumar]

Looks like numpy>=2.0 issue with pyoculus. I solved a similar issue for VMEC. Perhaps it could be replicated here. I'll do a more thorough check and get back to you.

[mbkumar]

In VMEC, we moved away from numpy.distutils which is deprecated and not working properly anymore. Pyoculus is still using numpy.distutils. This approach should be updated and a more robust setup function such as the one from scikit-build should be used.
@smiet used a meson build system for SPEC. Perhaps he may be interested in using the same one for PyOculus. Otherwise, I can take the lead and update the build system to a new one based on scikit-build and cmake.