Fix building issue on Xcode 16

Sources/General/Kingfisher.swift

@@ -36,7 +36,11 @@ public typealias KFCrossPlatformImageView   = NSImageView
 public typealias KFCrossPlatformButton      = NSButton
 
 // `NSImage` is not yet Sendable. We have to assume it sendable to resolve warnings in Kingfisher.
+#if swift(>=6)
+extension KFCrossPlatformImage: @retroactive @unchecked Sendable { }
+#else
 extension KFCrossPlatformImage: @unchecked Sendable { }
+#endif // swift(>=6)
 #else // os(macOS)
 import UIKit
 public typealias KFCrossPlatformImage       = UIImage

Sources/Image/Image.swift

@@ -27,8 +27,8 @@
 
 #if os(macOS)
 import AppKit
-private let imagesKey = malloc(1)!
-private let durationKey = malloc(1)!
+nonisolated(unsafe) private let imagesKey = malloc(1)!
+nonisolated(unsafe) private let durationKey = malloc(1)!
 #else
 import UIKit
 import MobileCoreServices

Sources/Utility/DisplayLink.swift

@@ -75,10 +75,17 @@ extension NSView {
 
 #if swift(>=5.9)
 @available(macOS 14.0, *)
-extension CADisplayLink: DisplayLinkCompatible, @unchecked Sendable {
+extension CADisplayLink: DisplayLinkCompatible {
     var preferredFramesPerSecond: NSInteger { return 0 }
 }
-#endif
+#if swift(>=6)
+@available(macOS 14.0, *)
+extension CADisplayLink: @retroactive @unchecked Sendable { }
+#else // swift(>=6)
+@available(macOS 14.0, *)
+extension CADisplayLink: @unchecked Sendable { }
+#endif // swift(>=6)
+#endif // swift(>=5.9)
 
 final class DisplayLink: DisplayLinkCompatible, @unchecked Sendable {
     private var link: CVDisplayLink?