Fix setup.py

Author: chunfantasy

setup.py

@@ -113,8 +113,8 @@ def find_version(*file_paths):
 
         'Programming Language :: Python',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.6'
-        'Programming Language :: Python :: 3.7'
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8'
     ],
     keywords='nordic nrf51 nrf52 ble bluetooth softdevice serialization bindings pc-ble-driver pc-ble-driver-py '