Use upper constraints from opendev.org

tox_install.sh uses curl w/o -L switch so it fails to account for
redirects that are now in place for backward compat with
git.openstack.org.

Use proper new location of upper constraints instead.

Change-Id: Ic4ad019197b3a5655bd0b8599931792740d0a516
Related-Issue: PROD-29707
diff --git a/tox.ini b/tox.ini
index 4431289..577ce75 100644
--- a/tox.ini
+++ b/tox.ini
@@ -23,7 +23,7 @@
 passenv = OS_STDOUT_CAPTURE OS_STDERR_CAPTURE OS_TEST_TIMEOUT OS_TEST_LOCK_PATH TEMPEST_CONFIG TEMPEST_CONFIG_DIR http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY ZUUL_CACHE_DIR REQUIREMENTS_PIP_LOCATION GENERATE_TEMPEST_PLUGIN_LIST
 usedevelop = True
 install_command =
-    {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?h=83b1de74834fbcdbe749e270c29e76cdc28f85d5} {opts} {packages}
+    {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/commit/83b1de74834fbcdbe749e270c29e76cdc28f85d5/upper-constraints.txt} {opts} {packages}
 whitelist_externals = *
 deps =
     -r{toxinidir}/requirements.txt