Handle mix version when running docker-ejabberd/ecs/build.sh latest

mix.exs

@@ -24,6 +24,7 @@ defmodule Ejabberd.MixProject do
     case config(:vsn) do
       :false -> "0.0.0" # ./configure wasn't run: vars.config not created
       '0.0' -> "0.0.0" # the full git repository wasn't downloaded
+      'latest.0' -> "0.0.0" # running 'docker-ejabberd/ecs/build.sh latest'
       [_, _, ?., _, _] = x ->
         head = String.replace(:erlang.list_to_binary(x), ~r/0+([0-9])/, "\\1")
         <<head::binary, ".0">>