Update git submodules

* Update plugins/singleusergroup from branch 'master'
  to 3548ec83c0c271a8768a6b03b0c28711521ed6cf
  - SingleUserGroup: Remove unused import
    
    Signed-off-by: Edwin Kempin <ekempin@google.com>
    Change-Id: I15dd3a9aca45f334ddf4d8febd859d966421493e
    
diff --git a/plugins/singleusergroup b/plugins/singleusergroup
index a0c53c6..3548ec8 160000
--- a/plugins/singleusergroup
+++ b/plugins/singleusergroup
@@ -1 +1 @@
-Subproject commit a0c53c6c5ad1ba8f8967ed6d2bcb18995f734cad
+Subproject commit 3548ec83c0c271a8768a6b03b0c28711521ed6cf