fix setup

Author: SkafteNicki

setup.py

@@ -65,7 +65,11 @@ def run(self):
         "Operating System :: OS Independent",
         # Specify the Python versions you support here. In particular, ensure
         # that you indicate whether you support Python 2, Python 3 or both.
+        "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
     ],
     cmdclass={"clean": CleanCommand},
 )