Update dependency gettext to ~> 0.23

mix.exs

@@ -54,7 +54,7 @@ defmodule Campfire.MixProject do
       {:swoosh, "~> 1.3"},
       {:telemetry_metrics, "~> 0.6"},
       {:telemetry_poller, "~> 1.0"},
-      {:gettext, "~> 0.22"},
+      {:gettext, "~> 0.23"},
       {:jason, "~> 1.4"},
       {:plug_cowboy, "~> 2.5"},
       {:bcrypt_elixir, "~> 3.0"}