Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 1973be329527f1475574047a86e09215a88b2831
  - Force install in non interactive mode

    Change-Id: Iabb004850da8d48d5e86ce043c01244f527a74fc
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index cbdd1a0..1973be3 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit cbdd1a0c0353e37a90f584346d0df218703d262a
+Subproject commit 1973be329527f1475574047a86e09215a88b2831