Set the minimum version of ex_aws to 2.1.2.

Author: darrenklein

mix.exs

@@ -54,7 +54,7 @@ defmodule ExAws.Dynamo.Mixfile do
   defp ex_aws() do
     case System.get_env("AWS") do
       "LOCAL" -> {:ex_aws, path: "../ex_aws"}
-      _ -> {:ex_aws, "~> 2.1"}
+      _ -> {:ex_aws, ">= 2.1.2"}
     end
   end
 end