Switch license type reference

Author: kchason

setup.cfg

@@ -22,7 +22,7 @@ classifiers =
     # E.g.:
     # Development Status :: 3 - Alpha
     Enviroment :: Console
-    License :: Public Domain
+    License :: OSI Approved :: Apache Software License
     Operating System :: OS Independent
     Programming Language :: Python :: 3
     Topic :: Software Development :: Testing