Pleroma.MFA: fix gradient error

lib/pleroma/mfa.ex: The map %{error: msg} on line 80 is expected to have type {:ok, list(binary())} | {:error, String.t()} but it has type %{required(:error) => any()}

lib/pleroma/mfa.ex

@@ -77,7 +77,7 @@ def generate_backup_codes(%User{} = user) do
       {:ok, codes}
     else
       {:error, msg} ->
-        %{error: msg}
+        {:error, msg}
     end
   end