MNT: Add Python 3.11 support to package metadata

Author: dopplershift

setup.cfg

@@ -18,6 +18,7 @@ classifiers =
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
+    Programming Language :: Python :: 3.11
     Topic :: Scientific/Engineering
     Topic :: Scientific/Engineering :: Atmospheric Science
     Intended Audience :: Science/Research