Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - xci: file: Update package metadata before installing packages

    We may have old or no metadata for packages at all so package
    installations may fail. As such, lets sync with upstream mirrors
    before we try to install any packages.

    Change-Id: I15f73e46d4f0cae2c50d23a92e0f4da83821039e
    Signed-off-by: Markos Chandras <mchandras@suse.de>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index 18a9798..e728ad6 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit 18a97988b9cf90dc92d6d9abbb7420c64ed6a0e1
+Subproject commit e728ad6988a15c71376860b1ea6eaedcce15fa4e