Update git submodules

* Update docs/submodules/apex from branch 'stable/euphrates'
  - Adding unittests for build

    - covers build.py
    - covers build_utils.py
    - moved build_utils out of build module, it wasn't possible to import
      build.py while build_utils was in a module

    Change-Id: I42f08a475d9ca219a62c421d4bdd2d1d3c49691a
    Signed-off-by: Dan Radez <dradez@redhat.com>
    (cherry picked from commit c876e9d261a7c3189cc8374c995014309c5b9881)

diff --git a/docs/submodules/apex b/docs/submodules/apex
index f3c3009..96e8ffe 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit f3c3009535b3c64f3cf2031fbc304d1835525409
+Subproject commit 96e8ffec3e9534f4cc131303334cb2d93179feed