BLD: remove distutil from setup.py

[sabonerune]

Remove distutil from setup.py

• Remove distutils.version.LooseVersion.

  Cython version checking is done in pyproject.toml so there is no need to check it.

  The ability to build if you have a .cpp files even if Cython is not installed will continue to be supported. ref: https://setuptools.pypa.io/en/latest/userguide/ext_modules.html#distributing-extensions-compiled-with-cython

• Remove distutils.spawn.spawn and distutils.errors.DistutilsExecError.

  https://github.com/r9y9/pyopenjtalk/blob/48dd78cafc954c8aff26a64b5c7ed54a8d0a3fb9/setup.py#L111-L172 This bug seems to have been patched by setuptools>=60.0.0. Therefore, this code can be made unnecessary by changing the version of setuptools only on Windows.

  It may be better to upgrade the version of setuptools on other OS as well. However, since I can't reproduce #27 , So I leave it as is.