Update TOX_CONSTRAINTS_FILE for stable/yoga

Update the URL to the upper-constraints file to point to the redirect
rule on releases.openstack.org so that anyone working on this branch
will switch to the correct upper-constraints list automatically when
the requirements repository branches.

Until the requirements repository has as stable/yoga branch, tests will
continue to use the upper-constraints list on master.

Change-Id: I25af3dba16b901398a3ff603cfc388d91633ad9c

Author: openstackadmin

tox.ini

@@ -9,7 +9,7 @@ basepython = python3
 usedevelop=True
 allowlist_externals = find
                       rm
-deps = -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+deps = -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/yoga}
        -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
@@ -55,14 +55,14 @@ commands = bandit -r docker kolla tests tools
 
 [testenv:venv]
 deps =
-    -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+    -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/yoga}
     -r{toxinidir}/test-requirements.txt
     -r{toxinidir}/doc/requirements.txt
 commands = {posargs}
 
 [testenv:docs]
 deps =
-    -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+    -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/yoga}
     -r{toxinidir}/doc/requirements.txt
 
 commands =