setup.cfg: fix classifiers (#120)

Author: davidhewitt

setup.cfg

@@ -14,7 +14,6 @@ classifiers =
     License :: OSI Approved :: MIT License
     Intended Audience :: Developers
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.5
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8