Update TOX_CONSTRAINTS_FILE for stable/2023.1

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/2023.1 branch, tests will
continue to use the upper-constraints list on master.

Change-Id: I1666c54961f194c3a615b6845c3a2a33eda9c070

tox.ini

@@ -23,7 +23,7 @@ setenv =
 # clue for oslo.db to use file-based database.
   OS_TEST_DBAPI_ADMIN_CONNECTION=sqlite:////tmp/placeholder-never-created-nor-used.db
 usedevelop = True
-install_command = python -m pip install -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
+install_command = python -m pip install -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2023.1} {opts} {packages}
 deps = -r{toxinidir}/test-requirements.txt
        -r{toxinidir}/requirements.txt
 commands =