fix: Ensure "show existing user" test passes reliably

Make the output of mix "mobilizon.users.show" deterministic by sorting actors before displaying them.

Fixes #1799

lib/mix/tasks/mobilizon/users/show.ex

@@ -45,6 +45,8 @@ defmodule Mix.Tasks.Mobilizon.Users.Show do
   defp display_actors([]), do: ""
 
   defp display_actors(actors) do
+    actors = Enum.sort_by(actors, & &1.id)
+
     """
     Identities (#{length(actors)}):
     #{Enum.map_join(actors, &display_actor/1)}