mastodon api: get_visibility(): DMs never have a cc list.

lib/pleroma/web/mastodon_api/views/status_view.ex

@@ -231,6 +231,9 @@ def get_visibility(object) do
       Enum.any?(to, &String.contains?(&1, "/followers")) ->
         "private"
 
+      length(cc) > 0 ->
+        "private"
+
       true ->
         "direct"
     end