Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [salt-formulas] Also switch reclass to 'testing'

    Previous commit only changed the dist during Salt master bootstrap,
    but failed to update the DEB repo configration in reclass.

    Fixes: a8f43411

    Change-Id: Ie011719cdc1c75cba363f53e51f22ce7cf138a5e
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index a8f4341..b52ef6e 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit a8f434118013a69295bdc0f9fc8294c539742c01
+Subproject commit b52ef6ea62f43de4b91e2becd92a3282e569925c