9.0.0-beta1

• Add support for Swift Package Manager (resolves #155)
• Breaking changes
  • Bump minimum supported deployment target to iOS 12.0
  • Require Braintree ~> 5.3.0
  • BraintreeApplePay, BraintreeVenmo and BraintreeUnionPay are now required dependencies
  • Make headers private:
    • BTCardFormViewController
    • BTDropInBaseViewController
    • BTPaymentSelectionViewController
    • BTVaultManagementViewController
  • Add BTDropInUICustomization, which replaces BTUIKAppearance for customizing UI
  • Enable Dynamic Type by default. This can be disabled with the disableDynamicType property on BTDropInUICustomization.
  • Show last four digits of vaulted cards, instead of "••• ••11", which truncates in larger fonts.
  • Remove support for Turkish localization
  • Remove BraintreeUIKit framework
  • Use number pad for expiration date input on card form
  • Require two-digit year for expiration date instead of four-digit year
  • Remove Carthage support
  • Change spelling of isCancelled property on BTDropInResult to isCanceled