tox.ini: Add py38 and remove py34
diff --git a/tox.ini b/tox.ini
index f0df1f6..8d1e42d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py27,pypy,py34,py35,py36,py37
+envlist = py27,pypy,py35,py36,py37,py38
 
 [testenv]
 deps =