Drop support for EOL Python 3.3
diff --git a/setup.py b/setup.py
index 81302bf..dc237c8 100755
--- a/setup.py
+++ b/setup.py
@@ -35,12 +35,14 @@
               'License :: OSI Approved :: Apache Software License',
               'Operating System :: OS Independent',
               'Programming Language :: Python',
+              'Programming Language :: Python :: 2',
               'Programming Language :: Python :: 2.7',
               'Programming Language :: Python :: 3',
-              'Programming Language :: Python :: 3.3',
               'Programming Language :: Python :: 3.4',
               'Programming Language :: Python :: 3.5',
               'Programming Language :: Python :: 3.6',
+              'Programming Language :: Python :: Implementation :: CPython',
+              'Programming Language :: Python :: Implementation :: PyPy',
               'Topic :: Security :: Cryptography',
           ],
           install_requires=[