Added the available for internal helper method

Author: dreampiggy

SDWebImageSwiftUI/Classes/SwiftUICompatibility.swift

@@ -66,6 +66,7 @@ class PlatformAppearView: PlatformView {
 
 #endif
 
+@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
 extension View {
     /// Used UIKit/AppKit behavior to detect the SwiftUI view's visibility.
     /// This hack is because of SwiftUI 1.0/2.0 buggy behavior. The built-in `onAppear` and `onDisappear` is so massive on some cases. Where UIKit/AppKit is solid.