Make truetype_metrics required

With some of the changes in v0.11 it appears that truetype_metrics is
now required for projects so make it non-optional. Also remove `runtime:
false` because it has no effect on truetype_metrics because
truetype_metrics does not start a supervision tree.

Author: axelson

mix.exs

@@ -49,10 +49,10 @@ defmodule Scenic.Mixfile do
       {:font_metrics, "~> 0.5.0"},
       {:nimble_options, "~> 0.3.4"},
       {:ex_image_info, "~> 0.2.4"},
+      {:truetype_metrics, "~> 0.5"},
 
       # Tools
       {:elixir_make, "~> 0.6.2", runtime: false},
-      {:truetype_metrics, "~> 0.5", only: [:dev, :test], runtime: false},
       {:ex_doc, ">= 0.0.0", only: :dev, runtime: false},
       {:credo, ">= 0.0.0", only: [:dev, :test], runtime: false},
       {:excoveralls, ">= 0.0.0", only: :test, runtime: false},