Mark support for Python 3.11

Travis previously gave an error, but Travis won't run for me anymore without paying, so I can't reproduce the issue. Tests pass in a python:3.11-slim docker container.

Fixes #97

Author: JoshData

.travis.yml

@@ -9,7 +9,7 @@ python:
 - '3.8'
 - '3.9'
 - '3.10'
-#- '3.11'
+- '3.11'
 - '3.12-dev'
 
 install:

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 :: Software Development :: Libraries :: Python Modules
 keywords = email address validator