Fixed typo.

Author: owo

setup.py

@@ -46,7 +46,7 @@
     'Natural Language :: Arabic',
     'Operating System :: OS Independent',
     'Programming Language :: Python :: 3',
-    'Programming Language :: Python :: 3 :: Only'
+    'Programming Language :: Python :: 3 :: Only',
     'Programming Language :: Python :: 3.7',
     'Programming Language :: Python :: 3.8',
     'Programming Language :: Python :: 3.9',