Update site icon spinner style

Author: kean

WordPress/Classes/ViewRelated/Blog/Blog Details/Detail Header/SiteIconView.swift

@@ -34,6 +34,7 @@ class SiteIconView: UIView {
 
     let activityIndicator: UIActivityIndicatorView = {
         let indicatorView = UIActivityIndicatorView(style: .medium)
+        indicatorView.color = .white
         indicatorView.translatesAutoresizingMaskIntoConstraints = false
         return indicatorView
     }()