Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "xci: bifrost: Only use libvirt as DNS server if using proxy servers"
  - xci: bifrost: Only use libvirt as DNS server if using proxy servers

    Commit 0d332a80cf731e5927c81c9f6929a8b83d43cddd ("Add proxy support")
    switched the default DNS server to the libvirt bridge. However, we only
    need to override the default DNS if we are behind a proxy server.

    Change-Id: I7d8fe8c10a1aba2db4a703a81e74ef76fa593d95
    Signed-off-by: Markos Chandras <mchandras@suse.de>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index efc57cd..455ea6c 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit efc57cd6b442eb16cddd1f383591aba87f72694d
+Subproject commit 455ea6c732384de5616be9c8c5cb006ae38e6716