Update git submodules

Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Fix the versions of openstack python client in Dovetail container

    1. Now the openstack python clients installed are always the latest.
    2. Fix them to certain versions according to the openstack requirements.
    3. The first version openstack requirements provided is newton.
    https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?h=stable/newton

    JIRA: DOVETAIL-615

    Change-Id: I107f8d3a4dbd95af3441c0ba410de37ba8128be3
    Signed-off-by: xudan <xudan16@huawei.com>