tox: add Python 3.8

LudovicRousseau · LudovicRousseau · commit faf137e99d3f · 2020-05-15T15:46:36.000+02:00
diff --git a/tox.ini b/tox.ini
@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py27,py37
+envlist = py27,py37,py38
 
 [testenv]
 whitelist_externals = cp
