Compatibility with latest Spicetify release

What's Changed

• feat(theme script): use Spicetify.Player.data.item by @SunsetTechuila in #53
• Compatibility patch for Upcoming Song extension by @SnowSquire in #54

New Contributors

• @SunsetTechuila made their first contribution in #53
• @SnowSquire made their first contribution in #54

Full Changelog: 4.7...4.8