refactor: made GamepadReader an interface

Program.cs

@@ -1,7 +1,7 @@
 namespace SwitchSlidePresenter {
 	class Program {
 		private static async Task Main() {
-			GamepadReader reader = new JoyConRead();
+			IGamepadReader reader = new JoyConRead();
 			SlideSwitcher switcher = new(reader);
 			await reader.Read();
 			switcher.Dispose();