Does not build with python 3.12

[sbird]

numpy.distutils has been removed, see here:
https://numpy.org/doc/stable/reference/distutils_status_migration.html

Simply replacing numpy.distutils with distutils does not quite work:

[spb41]~/codes/classylss% python setup.py install
/usr/lib/python3.12/site-packages/setuptools/_distutils/cmd.py:66: SetuptoolsDeprecationWarning: setup.py install is deprecated.
!!

    ********************************************************************************
    Please avoid running ``setup.py`` directly.
    Instead, use pypa/build, pypa/installer or other
    standards-based tools.

    See https://blog.ganssle.io/articles/2021/10/setup-py-deprecated.html for details.
    ********************************************************************************

!!
self.initialize_options()
/usr/lib/python3.12/site-packages/setuptools/_distutils/cmd.py:66: EasyInstallDeprecationWarning: easy_install command is deprecated.
!!

    ********************************************************************************
    Please avoid running ``setup.py`` and ``easy_install``.
    Instead, use pypa/build, pypa/installer or other
    standards-based tools.

    See https://github.com/pypa/setuptools/issues/917 for details.
    ********************************************************************************

!!
self.initialize_options()
error: in 'libraries' option (library 'class'), 'sources' must be present and must be a list of source filenames

[sbird]

@rainwoodman Any ideas?

[sbird]

This also means that fastpm does not pip install with python 3.12