Merge "Force constraints when installing a package during tox test"

tox.ini

@@ -1,8 +1,9 @@
 [tox]
-minversion = 3.18.0
+minversion = 4.4.0
 envlist = py3,functional,pep8
 
 [testenv]
+constrain_package_deps = true
 usedevelop = True
 setenv =
   VIRTUAL_ENV={envdir}
@@ -51,6 +52,7 @@ deps =
     flake8-import-order~=0.18.0 # LGPLv3
     pycodestyle>=2.0.0,<3.0.0 # MIT
     doc8~=1.1.0 # Apache-2.0
+    -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
 allowlist_externals = bash
                       {toxinidir}/tools/run_bashate.sh
 commands =