Update Poison version to match Phoenix

Author: Josh Price

mix.exs

@@ -28,7 +28,7 @@ defmodule GraphQL.Plug.Mixfile do
  {:ex_doc, "~> 0.11", only: :dev},
  {:cowboy, "~> 1.0"},
  {:plug, "~> 0.14 or ~> 1.0"},
- {:poison, "~> 2.1"},
+ {:poison, "~> 1.5 or ~> 2.0"},
  {:graphql, "~> 0.1.2"}]
  end
 

mix.lock

@@ -4,5 +4,5 @@
  "ex_doc": {:hex, :ex_doc, "0.11.0"},
  "graphql": {:hex, :graphql, "0.1.2"},
  "plug": {:hex, :plug, "1.0.2"},
- "poison": {:hex, :poison, "1.5.0"},
+ "poison": {:hex, :poison, "2.1.0"},
  "ranch": {:hex, :ranch, "1.2.0"}}