Updated from OpenStack Ansible Tests

Change-Id: I485b6ec7c8ccb5798eb2e5c5d2c047899eba391b

Vagrantfile

@@ -51,13 +51,8 @@ Vagrant.configure(2) do |config|
     leap150.vm.box = "opensuse/openSUSE-15.0-x86_64"
   end
 
-  config.vm.define "opensuse151" do |leap150|
+  config.vm.define "opensuse151" do |leap151|
-    leap150.vm.box = "opensuse/openSUSE-15.1-x86_64"
+    leap151.vm.box = "opensuse/openSUSE-15.1-x86_64"
-  end
-
-  config.vm.define "ubuntu1604" do |xenial|
-    xenial.disksize.size = "40GB"
-    xenial.vm.box = "ubuntu/xenial64"
   end
 
   config.vm.define "ubuntu1804" do |bionic|

doc/requirements.txt

@@ -2,8 +2,15 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-# this is required for the docs build jobs
+# WARNING:
-sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
+# This file is maintained in the openstack-ansible-tests repository.
+# https://opendev.org/openstack/openstack-ansible-tests/src/branch/master/sync/doc/requirements.txt
+# If you need to modify this file, update the one in the
+# openstack-ansible-tests repository. Once it merges there, the changes will
+# automatically be proposed to all the repositories which use it.
+
+sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7'  # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4'  # BSD
 openstackdocstheme>=1.18.1 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 doc8>=0.6.0 # Apache-2.0