Update git submodules

* Update docs/submodules/snaps from branch 'master'
  - openstack: nova_utils_tests: Wait for volume detachment

    The 'test_add_remove_volum' is supposed to wait for volume attachment
    and detachments. However, the code for the latter was missing. Moreover,
    we remove some code that checks for attached volumes since that should
    never happen when detaching the volume.

    Change-Id: I9ed54a467062d0ddc4efeddf03af7ebe6173e789
    Signed-off-by: Markos Chandras <mchandras@suse.de>

diff --git a/docs/submodules/snaps b/docs/submodules/snaps
index 91b3bcb..f355391 160000 (submodule)
--- a/docs/submodules/snaps
+++ b/docs/submodules/snaps
@@ -1 +1 @@
-Subproject commit 91b3bcb7ad2dda9479d2f97b080d8665d83968dd
+Subproject commit f3553913925b8ee5869c8e06047d6e4161a968c7