feat: add support for Python 3.9 / 3.10 (#220)

support for python 3.9 and 3.10

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Fixes #221

setup.py

@@ -67,6 +67,8 @@
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "Operating System :: OS Independent",
         "Topic :: Internet",
     ],