build: Use setuptools instead of distutils

setup.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-from distutils.core import setup
+from setuptools import setup, find_packages
 from pkg_resources import parse_requirements
 
 import hanja
@@ -19,14 +19,13 @@ def readme():
 
 setup(
     name="hanja",
-    py_modules=["hanja", "hanja/__init__", "hanja.hangul"],
     version=hanja.__version__,
     description="Hangul & Hanja library",
     long_description=readme(),
     author=hanja.__author__,
     author_email=hanja.__email__,
     url="https://github.com/suminb/hanja",
-    packages=[],
+    packages=find_packages(include=["hanja", "hanja.*"]),
     package_data={"": ["requirements.txt"], "hanja": ["table.yml"]},
     include_package_data=True,
     install_requires=install_requires,