Update libcdio.rb

version 0.91 is removed, noted as do not use, updating formula to bump to 0.92. Reference: http://git.savannah.gnu.org/gitweb/?p=libcdio.git;a=blob;f=NEWS;h=9fc0bbbf232ec095eab62feb16c84af036a2ad96;hb=3e409de021299fefce02029dbc61a958df40f29b