Fix haml-lint error

The error was introduced when merging

https://github.com/openSUSE/osem/pull/1469

as a offense was introduced since the tests there were run
and the PR got merged.

app/views/admin/users/index.html.haml

@@ -7,7 +7,7 @@
           = "(#{@users.length})"
         - if can? :create, User
           .pull-right
-            =link_to 'Add User', new_admin_user_path, :class => 'button btn btn-default btn-info'
+            = link_to 'Add User', new_admin_user_path, :class => 'button btn btn-default btn-info'
 .row
   .col-md-12.table-responsive
     %table.table.table-striped.table-bordered.table-hover.datatable