Use setuptools instead of distutils (#349)

distutils is deprecated

Author: jarrodmillman

setup.py

@@ -1,9 +1,7 @@
 import sys
 import os
 
-import setuptools  # may monkeypatch distutils in some versions. # noqa
-from distutils.command.sdist import sdist
-from distutils.core import setup
+from setuptools import setup
 
 from numpydoc import __version__ as version
 
@@ -60,5 +58,4 @@ def read(fname):
         'tests/tinybuild/*.py',
         'templates/*.rst',
         ]},
-    cmdclass={"sdist": sdist},
 )