Enable find interaction on iOS 16

Reader/Screens/Read/ReadViewController.swift

@@ -70,6 +70,9 @@ class ReadViewController: UIViewController {
         // transparent background required to prevent white flash in dark mode, just using .appBackground doesn't work
         webView.isOpaque = false
         webView.backgroundColor = .clear
+        if #available(iOS 16.0, *) {
+            webView.isFindInteractionEnabled = true
+        }
         if let content = itemContentHTML() {
             webView.loadHTMLString(content, baseURL: item.url)
         }