update link to upper-constraints.txt

Issue-ID: DOC-823

Change-Id: I2bca6dfe085ae21a6ba42dbc0da4ce1bea266ee2
Signed-off-by: thmsdt <thomas.kulik@telekom.de>
diff --git a/docs/tox.ini b/docs/tox.ini
index 379d8e4..102f675 100644
--- a/docs/tox.ini
+++ b/docs/tox.ini
@@ -7,7 +7,7 @@
 basepython = python3.8
 deps =
     -r{toxinidir}/requirements-docs.txt
-    -chttps://raw.githubusercontent.com/openstack/requirements/stable/yoga/upper-constraints.txt
+    -chttps://releases.openstack.org/constraints/upper/yoga
     -chttps://git.onap.org/doc/plain/etc/upper-constraints.onap.txt?h=master
 commands =
     sphinx-build -W -b html -n -d {envtmpdir}/doctrees ./ {toxinidir}/_build/html
@@ -21,7 +21,7 @@
 basepython = python3.8
 deps =
     -r{toxinidir}/requirements-docs.txt
-    -chttps://raw.githubusercontent.com/openstack/requirements/stable/yoga/upper-constraints.txt
+    -chttps://releases.openstack.org/constraints/upper/yoga
     -chttps://git.onap.org/doc/plain/etc/upper-constraints.onap.txt?h=master
 commands = echo "Link Checking not enforced"
 #commands = sphinx-build -W -b linkcheck -d {envtmpdir}/doctrees ./ {toxinidir}/_build/linkcheck
@@ -31,7 +31,7 @@
 basepython = python3.8
 deps =
     -r{toxinidir}/requirements-docs.txt
-    -chttps://raw.githubusercontent.com/openstack/requirements/stable/yoga/upper-constraints.txt
+    -chttps://releases.openstack.org/constraints/upper/yoga
     -chttps://git.onap.org/doc/plain/etc/upper-constraints.onap.txt?h=master
 commands =
     sphinx-build -W -q -b spelling -d {envtmpdir}/doctrees {toxinidir} {toxinidir}/_build/spellcheck