Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Update blacklist about migration tests for rally

    The test NovaServers.boot_and_migrate_server needs at least 2 compute
    nodes:
    https://github.com/openstack/rally/blob/stable/0.9/rally/plugins/openstack/scenarios/nova/servers.py#L763-L765

    Change-Id: I4ddf99188094ced57225d886037b00e91f3b68e6
    Signed-off-by: Linda Wang <wangwulin@huawei.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 969e450..613c672 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 969e4500ad7fe516b1d89d97d36c4a6d851fb6c6
+Subproject commit 613c672ac166ca92ce1284131ec06446e07e0023