Update git submodules

* Update docs/submodules/releng from branch 'master'
  to f426669dd26e7d24ce6a13bc0af38d43be758658
  - Update Xtesting Gates

    It now selects lf-virtual1 as slave and Alpine 3.10.
    It has been generated via latest Xtesting Ansible role.

    Change-Id: I97c2179cc0f42e435e19b738f7d86114de592425
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 6f49658..f426669 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 6f496588ed030772c6acf3256fc134515b8e5f05
+Subproject commit f426669dd26e7d24ce6a13bc0af38d43be758658