Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Stop verifying Functest Euphrates"
  - Stop verifying Functest Euphrates

    Functest Euphrates is now EOL (jjobs creating containers has already
    been removed)

    Change-Id: I668137b2701d073ce95856fa20dc54135a6cc111
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index c87d100..2d21063 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit c87d1004da7339738f19ee909bad50e6f9bc9941
+Subproject commit 2d21063f73d9d949ffdd31ec2c0412516f83e1a6