iOS implementation uses deprecated Storekit 1 framework

[felixkrautschuk]

Hi, I just noticed that the iOS implementation of this plugins uses the old Storekit 1 (SKPaymentQueue, SKProduct, ...) which is deprecated since iOS 18.

https://developer.apple.com/documentation/storekit/skpaymentqueue?language=objc

However, I guess it still will work for a while.