Replace git.openstack.org URLs with opendev.org URLs

Change-Id: I3836f1c839ca36b320b3f42d724f594f2d7b12ee
Closes-Bug: #1826196

README.rst

@@ -25,6 +25,6 @@ strings in an application or library.
 
 * Free software: Apache license
 * Documentation: https://docs.openstack.org/oslo.i18n/latest
-* Source: https://git.openstack.org/cgit/openstack/oslo.i18n
+* Source: https://opendev.org/openstack/oslo.i18n
 * Bugs: https://bugs.launchpad.net/oslo.i18n
 * Release notes:  https://docs.openstack.org/releasenotes/oslo.i18n/

tox.ini

@@ -5,7 +5,7 @@ envlist = py37,py27,pep8
 [testenv]
 install_command = pip install {opts} {packages}
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
  -r{toxinidir}/test-requirements.txt
  -r{toxinidir}/requirements.txt
 commands = stestr run --slowest {posargs}