feat: add support for Python 3.10 (#882)

diff --git a/setup.py b/setup.py
index 54a2c90..343e660 100644
--- a/setup.py
+++ b/setup.py
@@ -63,6 +63,7 @@
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "Development Status :: 5 - Production/Stable",
         "Intended Audience :: Developers",
         "License :: OSI Approved :: Apache Software License",