Add tvos to platform support for the Storage UI

Author: netizen01

FirebaseUI.podspec

@@ -32,7 +32,8 @@ Pod::Spec.new do |s|
   end
 
   s.subspec 'Storage' do |storage|
-    storage.platform = :ios, '8.0'
+    storage.ios.deployment_target = '8.0'
+    storage.tvos.deployment_target = '11.0'
     storage.public_header_files = 'Storage/FirebaseStorageUI/*.h'
     storage.source_files = 'Storage/FirebaseStorageUI/*.{h,m}'
     storage.dependency 'Firebase/Storage', '~> 6.0'