[ci skip] fix Package.swift

Author: srea

Package.swift

@@ -3,7 +3,7 @@ import PackageDescription
 
 let package = Package(
     name: "RIBsTreeViewerClient",
-    platforms: [.iOS(.v13)],
+    platforms: [.iOS(.v8)],
     products: [
         .library(name: "RIBsTreeViewerClient", targets: ["RIBsTreeViewerClient"]),
     ],

RIBsTreeViewerClient/Sources/RIBsTreeViewer.swift

@@ -7,6 +7,7 @@
 //
 
 import Foundation
+import UIKit
 import RxSwift
 import RIBs