fix: thumbnail color buttons missing border transparency

Author: Bentroen

apps/frontend/src/modules/song/components/client/SongThumbnailInput.tsx

@@ -123,7 +123,7 @@ const ColorButton: React.FC<ColorButtonProps> = ({
       <button
         type='button'
         className={cn(
-          'w-6 h-6 rounded-full flex-none border-2 border-zinc-200 border-opacity-30 disabled:opacity-30',
+          'w-6 h-6 rounded-full flex-none border-2 border-zinc-200/30 disabled:opacity-30',
           active && 'outline outline-2 outline-zinc-200',
         )}
         style={{ backgroundColor: color }}