Use setuptools declarative syntax via setup.cfg

https://setuptools.readthedocs.io/en/latest/userguide/declarative_config.html

This avoids mixing code and configuration, reduces boilerplate, and
avoids custom logic at installation time.

setup.cfg

@@ -0,0 +1,25 @@
+[matadata]
+name = freezegun
+version = attr: freezegun.__version__
+description = Let your Python tests travel through time
+long_description = file: README.rst
+author = Steve Pulec
+author_email = [email protected]
+url = https://github.com/spulec/freezegun
+license = Apache 2.0
+classifiers =
+    License :: OSI Approved :: Apache Software License
+    Programming Language :: Python :: 3
+    Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3.8
+    Programming Language :: Python :: Implementation :: CPython
+    Programming Language :: Python :: Implementation :: PyPy
+
+[options]
+packages = freezegun
+python_requires = >=3.5
+install_requires =
+    python-dateutil >= 2.7
+include_package_data = true

setup.py

@@ -1,42 +1,4 @@
 #!/usr/bin/env python
-import os
-import re
-
 from setuptools import setup
 
-with open('README.rst') as f:
-    readme = f.read()
-
-
-def read_version():
-    with open(os.path.join('freezegun', '__init__.py')) as f:
-        m = re.search(r'''__version__\s*=\s*['"]([^'"]*)['"]''', f.read())
-        if m:
-            return m.group(1)
-        raise ValueError("couldn't find version")
-
-
-setup(
-    name='freezegun',
-    version=read_version(),
-    description='Let your Python tests travel through time',
-    long_description=readme,
-    author='Steve Pulec',
-    author_email='[email protected]',
-    url='https://github.com/spulec/freezegun',
-    packages=['freezegun'],
-    install_requires=['python-dateutil>=2.7'],
-    include_package_data=True,
-    license='Apache 2.0',
-    python_requires='>=3.5',
-    classifiers=[
-        'License :: OSI Approved :: Apache Software License',
-        'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.5',
-        'Programming Language :: Python :: 3.6',
-        'Programming Language :: Python :: 3.7',
-        'Programming Language :: Python :: 3.8',
-        'Programming Language :: Python :: Implementation :: CPython',
-        'Programming Language :: Python :: Implementation :: PyPy',
-    ],
-)
+setup()