Update TOX_CONSTRAINTS_FILE for stable/2026.1

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/2026.1 branch, tests will
continue to use the upper-constraints list on master.

Change-Id: I60236e27e34588465169aa2fc4a81128701b95e2
Signed-off-by: OpenStack Release Bot <infra-root@openstack.org>
Generated-By: openstack/project-config:roles/copy-release-tools-scripts/files/release-tools/functions

.gitreview

@@ -2,3 +2,4 @@
 host=review.opendev.org
 port=29418
 project=openstack/python-watcherclient.git
+defaultbranch=stable/2026.1

tox.ini

@@ -8,7 +8,7 @@ passenv = ZUUL_CACHE_DIR
           REQUIREMENTS_PIP_LOCATION
 install_command = pip install {opts} {packages}
 deps =
-  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2026.1}
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 allowlist_externals =
@@ -40,7 +40,7 @@ commands =
 [testenv:docs]
 basepython = python3
 deps =
-  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2026.1}
   -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -W -b html doc/source doc/build/html