Don't use parentheses on 0-arity function definitions

lib/music_library/application.ex

@@ -37,7 +37,7 @@ defmodule MusicLibrary.Application do
     :ok
   end
 
-  defp skip_migrations?() do
+  defp skip_migrations? do
     # By default, sqlite migrations are run when using a release
     System.get_env("RELEASE_NAME") != nil
   end