Add missing comma to setup.py

Author: mattdodge

setup.py

@@ -23,8 +23,8 @@
         'License :: OSI Approved :: MIT License',
         'Topic :: Terminals :: Serial',
         'Programming Language :: Python',
-        'Programming Language :: Python :: 2'
-        'Programming Language :: Python :: 3'
+        'Programming Language :: Python :: 2',
+        'Programming Language :: Python :: 3',
     ],
     packages=find_packages(exclude=['tests', '*.tests']),
     install_requires=['pyserial']