user: make User.delete() return data consistent with Object.delete()

lib/mix/tasks/rm_user.ex

@@ -7,7 +7,7 @@ def run([nickname]) do
     Mix.Task.run("app.start")
 
     with %User{local: true} = user <- User.get_by_nickname(nickname) do
-      User.delete(user)
+      {:ok, _} = User.delete(user)
     end
   end
 end

lib/pleroma/user.ex

@@ -657,7 +657,7 @@ def delete(%User{} = user) do
       end
     end)
 
-    :ok
+    {:ok, user}
   end
 
   def html_filter_policy(%User{info: %{"no_rich_text" => true}}) do