Add BackgroundSource.Seasonal
Add BackgroundSource.Seasonal

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