Update min tox version to 2.0

The commands used by constraints need at least tox 2.0.
Update to reflect reality, which should help with local running of
constraints targets.

Change-Id: Ic6e6b6922309829c7a311bc255a269bd8a458fb7

1 files changed, 1 insertions, 1 deletions

diff --git a/tox.ini b/tox.ini
index dc9bd397..93773bb5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-minversion = 1.8
+minversion = 2.0
 skipsdist = True
 envlist = py{27,35},pep8