add 3.10 to trove classifiers

Author: graingert-coef

setup.py

@@ -68,6 +68,7 @@ def read_req_file(req_type):
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "Topic :: Database :: Front-Ends",
         "Topic :: Office/Business :: Financial :: Spreadsheet",
         "Topic :: Scientific/Engineering :: Visualization",