Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to 4bc9f720a16de97ba93f8184a9973703fa125f2e
  - Merge "fix sonar potential nullpointer"
  - fix sonar potential nullpointer

    AppcRunTasks: fix potential null pointer if vnf = null
    AppcRunTasksTest: add tests for this case and the method itself

    Change-Id: I63b37670541ef5ff31b03b0336d990677b753fc5
    Issue-ID: SO-1516
    Signed-off-by: k.kazak <k.kazak@samsung.com>

diff --git a/docs/submodules/so.git b/docs/submodules/so.git
index ac89233..4bc9f72 160000 (submodule)
--- a/docs/submodules/so.git
+++ b/docs/submodules/so.git
@@ -1 +1 @@
-Subproject commit ac892330d55c6a33f376f217fa6ec4464e361b02
+Subproject commit 4bc9f720a16de97ba93f8184a9973703fa125f2e