Add missing `readonly` keyword to new bindable
Add missing `readonly` keyword to new bindable

ppy/osu,NeoAdonis/osu,ppy/osu,smoogipoo/osu,ppy/osu,NeoAdonis/osu,smoogipooo/osu,smoogipoo/osu,peppy/osu,peppy/osu,smoogipoo/osu,peppy/osu-new,NeoAdonis/osu,peppy/osu