Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/danube'
  - Do not stop tests if exception in testcase

    Change-Id: I9e3db350be4b1ca60d6feaf2961034b50b50deb5
    Signed-off-by: Nikolas Hermanns <nikolas.hermanns@ericsson.com>
    (cherry picked from commit fbe69370c477a7b01032df701fe96ea90ec60341)

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 5c28dc1..6788c3b 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 5c28dc19e72ffbbaf652ff6b5c48d7fe72bdd9c4
+Subproject commit 6788c3b0ad67b65c41bbf8bf23a6a97561cf6e3a