Fix the Combine framework warning

Author: dreampiggy

SDWebImageSwiftUI/Classes/ImageManager.swift

@@ -7,6 +7,7 @@
  */
 
 import SwiftUI
+import Combine
 import SDWebImage
 
 /// A Image observable object for handle image load process. This drive the Source of Truth for image loading status.

SDWebImageSwiftUI/Classes/ImagePlayer.swift

@@ -7,6 +7,7 @@
  */
 
 import SwiftUI
+import Combine
 import SDWebImage
 
 /// A Image observable object for handle aniamted image playback. This is used to avoid `@State` update may capture the View struct type and cause memory leak.

SDWebImageSwiftUI/Classes/Indicator/Indicator.swift

@@ -7,6 +7,7 @@
 */
 
 import Foundation
+import Combine
 import SwiftUI
 
 /// A  type to build the indicator