Add Python 3.11 to setup.cfg

[skip ci]

setup.cfg

@@ -23,6 +23,7 @@ classifiers =
     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
     Topic :: Games/Entertainment
     Topic :: Multimedia