Update PyPI package classifiers

Author: amureki

setup.py

@@ -21,14 +21,10 @@ def readfile(filename):
     'Topic :: Internet :: WWW/HTTP :: Dynamic Content',
     'Topic :: Software Development :: Libraries :: Application Frameworks',
     'Development Status :: 5 - Production/Stable',
-    'Programming Language :: Python :: 3.6',
     'Programming Language :: Python :: 3.7',
     'Programming Language :: Python :: 3.8',
     'Programming Language :: Python :: 3.9',
     'Framework :: Django',
-    'Framework :: Django :: 2.2',
-    'Framework :: Django :: 3.0',
-    'Framework :: Django :: 3.1',
     'Framework :: Django :: 3.2',
     'Framework :: Django :: 4.0',
 ]