Adding Python 3.10 classifier

Author: mwatts15

setup.py

@@ -38,6 +38,7 @@
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "License :: OSI Approved :: BSD License",
         "Topic :: Software Development :: Libraries :: Python Modules",
         "Operating System :: OS Independent",