Run mix format on Elixir 12

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

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

@@ -58,11 +58,9 @@ defmodule Mix.Tasks.Mobilizon.Users.Modify do
       An user has been modified with the following information:
         - email: #{user.email}
         - Role: #{user.role}
-        - account status: #{
-        if user.confirmed_at,
-          do: "activated on #{DateTime.to_string(user.confirmed_at)} (UTC)",
-          else: "disabled"
-      }
+        - account status: #{if user.confirmed_at,
+        do: "activated on #{DateTime.to_string(user.confirmed_at)} (UTC)",
+        else: "disabled"}
       """)
     else
       {:makes_changes, false} ->