Update trove classifiers

Author: Code0x58

setup.py

@@ -30,6 +30,7 @@
         Programming Language :: Python :: 3.4
         Programming Language :: Python :: 3.5
         Programming Language :: Python :: 3.6
+        Programming Language :: Python :: 3.7
         Programming Language :: Python :: Implementation :: CPython
         Programming Language :: Python :: Implementation :: PyPy
     """).strip().split('\n'),