Add Python 3 Train unit tests

This is a mechanically generated patch to ensure unit testing is in place
for all of the Tested Runtimes for Train.

See the Train python3-updates goal document for details:
https://governance.openstack.org/tc/goals/train/python3-updates.html

Change-Id: If79694b32ece897c93d1889da28daff641e46f1c
Story: #2005924
Task: #34225

1 files changed, 1 insertions, 1 deletions

diff --git a/tox.ini b/tox.ini
index a5f18cc..5ef67b9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 # py3 first to avoid .testrepository incompatibility
-envlist = py36,py27,pypy,pep8
+envlist = py37,py27,pypy,pep8
 minversion = 2.3.2
 skipsdist = True