Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Fix broken L3VPN tests

    L3VPN IPv6 tests fail consistently. This patch checks out a version of
    CSIT right before an update was done to all the L3VPN test. This patch
    will be used to validate if the bug was introduced by that commit, and
    reverted either way.

    Change-Id: I2998cc7cfae183048e5ff1d06fd6bcdf16dd8e41
    Signed-off-by: Tim Rozet <trozet@redhat.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 76d6b19..20b922b 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 76d6b19a8ef7cefc948dceda3913413c5de4239d
+Subproject commit 20b922b492b6f6f3cc511bdc6623a31f4a06b637