Update the constraints url
For more detail, see http://lists.openstack.org/pipermail/openstack-discuss/2019-May/006478.html
Change-Id: Icecb2f54fd27fab4c43cc487dc9c434d3bb9ee48
diff --git a/tox.ini b/tox.ini
index 1f1ce01..faa94df 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,7 +5,7 @@
[testenv]
usedevelop = True
-install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
+install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
setenv =
VIRTUAL_ENV={envdir}
PYTHONWARNINGS=default::DeprecationWarning