installer/slideshow::fixed the deepin-music page fontSize too small

tower:https://tower.im/projects/8a6342c556be4c4eb898fdd7fd6fcb2f/todos/899a260f3af042beae7f08d996ab7094/#ad5b91e3db0b44fe8bc6eb8fb743fde1

Change-Id: Idcc178c78dcab7e7f715c682a3f3e7ed6dc41dcd