Merge pull request #1973 from onevcat/fix/empty-placeholder-loading

Overlay the placeholder view to allow onAppear executing

Sources/SwiftUI/KFImageRenderer.swift

@@ -46,7 +46,7 @@ struct KFImageRenderer<HoldingView> : View where HoldingView: KFImageHoldingView
             if binder.loadedImage == nil {
                 Group {
                     if let placeholder = context.placeholder, let view = placeholder(binder.progress) {
-                        view
+                        Color.clear.overlay(view)
                     } else {
                         Color.clear
                     }