[requires.io] dependency update

Author: requires

setup.py

@@ -34,16 +34,21 @@
           'idna>=2.5',
           'typing ; python_version<"3.5"',
       ],
+      python_requires='>=2.6, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*',
       classifiers=[
           'Topic :: Utilities',
           'Intended Audience :: Developers',
           'Topic :: Software Development :: Libraries',
           'Development Status :: 5 - Production/Stable',
+          'Programming Language :: Python :: 2',
           'Programming Language :: Python :: 2.6',
           'Programming Language :: Python :: 2.7',
+          'Programming Language :: Python :: 3',
           'Programming Language :: Python :: 3.4',
           'Programming Language :: Python :: 3.5',
           'Programming Language :: Python :: 3.6',
+          'Programming Language :: Python :: 3.7',
+          'Programming Language :: Python :: 3.8',
           'Programming Language :: Python :: Implementation :: PyPy',
           'License :: OSI Approved :: MIT License', ]
       )