Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - bifrost: Bump bifrost sha1s to latest on master

    This change brings in the fix for policy.json removal.

    https://review.openstack.org/#/c/536349/

    Change-Id: Ib18a99502c0ce61278e13f25a01622e073749d14
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index 23e3c26..34145f8 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit 23e3c26a3246a4a933710b7bb1845a077b015171
+Subproject commit 34145f8e2a87e5f6ab3ba9535e01a3d55524a812