add py3.11 to test matrices

Author: fgregg

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py27,py36,py37,py38,py39,py310
+envlist = py27,py36,py37,py38,py39,py310,py311
 
 [gh-actions]
 python =
@@ -9,6 +9,7 @@ python =
     3.8: py38
     3.9: py39
     3.10: py310
+    3.11: py310
 
 [testenv]
 changedir = {envtmpdir}