Installation challenges continue

[keflavich]

During my latest attempt on Mac OS X 13.6 Ventura, I ran into a series of problems:

1. The linked libraries moved location. That's fixed with 469483a and 5a10b43
2. My fortran compiler was producing x86_64 instead of arm64 files. I fixed that by installing an appropriate fortran version from https://github.com/fxcoudert/gfortran-for-macOS/releases
3. Python now complains loudly about calling the installer directly:

        ********************************************************************************
        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.
        ********************************************************************************

4. Setup no longer finds the correct .so file by default because there are files named ./pyradex/radex/radex.cpython-310-darwin.so etc (i.e., they're radex.<something>.so instead of radex.so). 3b0625f fixes that by globbing for precompiled .so objects, which we expect to find if python setup.py install_radex completed successfully.

So... install kinda works again on my mac at least.