Apply upper constraints to build documentation

... to avoid problems caused by the latest libraries.

Change-Id: I78b17bbfab6ca75a728c1438a942897c877ff469

tox.ini

@@ -10,9 +10,9 @@ setenv = OS_STDOUT_NOCAPTURE=False
          OS_STDERR_NOCAPTURE=False
 
 deps =
-       -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
-       -r{toxinidir}/requirements.txt
-       -r{toxinidir}/test-requirements.txt
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2025.1}
+  -r{toxinidir}/requirements.txt
+  -r{toxinidir}/test-requirements.txt
 commands = find . -type f -name "*.pyc" -delete
            stestr run --slowest {posargs}
 allowlist_externals = find
@@ -66,8 +66,9 @@ exclude = .venv,.tox,dist,doc,*egg,build
 [testenv:docs]
 commands = sphinx-build -W -b html doc/source doc/build/html
 deps =
-      -r{toxinidir}/doc/requirements.txt
-      -r{toxinidir}/requirements.txt
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2025.1}
+  -r{toxinidir}/doc/requirements.txt
+  -r{toxinidir}/requirements.txt
 
 [testenv:pdf-docs]
 deps = {[testenv:docs]deps}
@@ -81,7 +82,9 @@ commands =
 
 [testenv:releasenotes]
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
-deps = -r{toxinidir}/doc/requirements.txt
+deps =
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2025.1}
+  -r{toxinidir}/doc/requirements.txt
 
 [hacking]
 import_exceptions =