make all-media header translucent

deltachat-ios/Controller/AllMediaViewController.swift

@@ -38,6 +38,10 @@ class AllMediaViewController: UIPageViewController {
             animated: true,
             completion: nil
         )
+
+        if #available(iOS 13, *) {
+            self.navigationController?.navigationBar.scrollEdgeAppearance = self.navigationController?.navigationBar.standardAppearance
+        }
     }
 
     override func viewWillAppear(_ animated: Bool) {