Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - Merge "lib.sh: Fix compatibility with bash 4.2" into stable/euphrates
  - lib.sh: Fix compatibility with bash 4.2

    JIRA: FUEL-296

    Change-Id: Ide9f9333fe9b44ff6b78678064f8e67f05aabd42
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit fa62907da62d0b8ae9e733a9729941065ceedf4d)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 389271f..a9e172b 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 389271f828486c77aec3cdd5a3405bb6d090d4b0
+Subproject commit a9e172b43c5ab17b1c1971dbb6fccf2e66bbe520