Add Python 3.8 to the tox matrix (#135)

Allows contributors to easily run the full test matrix locally.

Python 3.8 was released on on October 14th, 2019.

https://docs.python.org/3/whatsnew/3.8.html

1 files changed, 1 insertions, 1 deletions

diff --git a/tox.ini b/tox.ini
index 572a2c7..888a816 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist=pypy3, py35, py36, py37
+envlist=py{35,36,37,38,py3}
 
 [testenv]
 deps=-rrequirements-dev.txt