Update setup.py

setup.py

@@ -21,6 +21,7 @@ setup(
         'License :: OSI Approved ::  GNU General Public License v3 (GPLv3)',
         'Natural Language :: English',
         'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3.6',
     ],
     description="View mseed headers",
     entry_points={