Remove deprecation warnings for Xcode beta4

Other Projects/Currency-SwiftUI/Currency-SwiftUI/UserData.swift

@@ -32,13 +32,13 @@ private let defaultCurrencies: [Currency] = [
     Currency(name: "Canadian dollar", rate: 1.0, symbol: "CA", code: "CAD")
 ]
 
-@propertyDelegate
+@propertyWrapper
 struct UserDefaultValue<Value: Codable> {
     
     let key: String
     let defaultValue: Value
     
-    var value: Value {
+    var wrappedValue: Value {
         get {
             let data = UserDefaults.standard.data(forKey: key)
             let value = data.flatMap { try? JSONDecoder().decode(Value.self, from: $0) }