bump explicitly supported versions in setup.py

Author: emlazzarin

setup.py

@@ -26,6 +26,8 @@
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
+        'Programming Language :: Python :: 3.9',
         'License :: OSI Approved :: MIT License'
     ],
     install_requires=['requests>=2.0', 'pandas>=0.25', 'lxml'],