Remove ``distutils`` use

[jobovy]

🐛 Bug

distutils is deprecated, so we need to replace/remove all of it's use in the code. Currently used in

• setup.py
• __intelcompiler.py
• ~galpy/util/_load_extension_libs.py~

[jobovy]

So far, have gotten rid of all distutils usage except for the compiler stuff in setup.py and __intelcompiler.py. My sense from reading setuptools discussions about this, is that it could be a while until there are decent replacements for that.

Leaving open for now. Note that while distutils will be removed from the standard library in Python 3.12 (Oct 2023), setuptools will probably ship its version that imports the same for longer, so this isn't a major and urgent issue.