tox.ini: add test environment for py3 ("latest" python 3)

I noticed that python 3.10 is my system default be we're testing
against py39 only. Keep python 3.9 as our lowest supported version
but also test the latest py3 available.


Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

tox.ini

@@ -1,6 +1,6 @@
 
 [tox]
-envlist = py39
+envlist = py39, py3
 isolated_build = True
 
 [testenv]