Re-enable compiler as warning

Author: code-shoily

mix.exs

@@ -8,8 +8,8 @@ defmodule AdventOfCode.MixProject do
       elixir: "~> 1.18",
       start_permanent: Mix.env() == :prod,
       aliases: aliases(),
-      deps: deps()
-      # elixirc_options: [warnings_as_errors: true]
+      deps: deps(),
+      elixirc_options: [warnings_as_errors: true]
     ]
   end