Update the constraints url
For more detail, see http://lists.openstack.org/pipermail/openstack-discuss/2019-May/006478.html
Change-Id: I51af25ca1d9666cdb2916220aa2e3c940057dff3
diff --git a/tox.ini b/tox.ini
index de73d26..a439f0f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,7 +5,7 @@
[testenv]
usedevelop = True
-install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/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