Add LED test

lib/test.ex

@@ -9,12 +9,18 @@ defmodule ExSpeedGame.Test do
   @impl true
   def init(_) do
     ExSpeedGame.Game.ButtonInput.acquire(ExSpeedGame.Game.ButtonInput)
-    {:ok, :ok}
+    {:ok, ref} = Circuits.GPIO.open(16, :output, initial_value: 0)
+    {:ok, {ref, false}}
   end
 
   @impl true
-  def handle_info(msg, s) do
+  def handle_info(msg, {ref, state}) do
     Logger.debug(inspect(msg))
-    {:noreply, s}
+
+    new_state = not state
+
+    Circuits.GPIO.write(ref, if(new_state, do: 1, else: 0))
+
+    {:noreply, {ref, new_state}}
   end
 end