Forgot to add classifiers when promoting 3.11 in #153 (#155)

Author: masklinn

setup.py

@@ -234,6 +234,7 @@ class sdist(_sdist):
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
+        "Programming Language :: Python :: 3.11",
         "Programming Language :: Python :: Implementation :: CPython",
         "Programming Language :: Python :: Implementation :: PyPy",
     ],