Works for Xcode 12 & 13

This is a change to Lumina that hits the following high notes:

• Compiles on Xcode 13.0b2
• Minimum iOS version compatibility of iOS 13.0
• Drops support for Cocoapods
• Drops support for Carthage
• Exclusive support for Swift Package Manager
• A handy-dandy sample app icon generated by Bakery (thanks, @jordibruin !!)

1.2.1

Compatible with Swift 4.1