Lightbox: Remove scrollbars when panning and zooming on iOS.

I don't think these really add anything.

Author: chrisbobbe

src/lightbox/Lightbox.js

@@ -76,6 +76,8 @@ export default function Lightbox(props: Props) {
         //   https://github.com/alwx/react-native-photo-view/issues/98
         // TODO: Figure out how to make it work.
         resizeMode="contain"
+        showsHorizontalScrollIndicator={false}
+        showsVerticalScrollIndicator={false}
         onTap={handleImagePress}
         onViewTap={handleImagePress}
       />