Remove Python 3.6 & add 3.11 trove classifier

Author: smheidrich

setup.cfg

@@ -14,11 +14,11 @@ classifiers =
     License :: OSI Approved :: MIT License
     Intended Audience :: Developers
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
+    Programming Language :: Python :: 3.11
     Development Status :: 5 - Production/Stable
     Operating System :: POSIX
     Operating System :: MacOS :: MacOS X