img: remove loading spinners

This adds blank space, but it will be nice if we can improve this
by either fading in or having some shimmer effect.

Signed-off-by: William Casarin <jb55@jb55.com>

src/app_style.rs

@@ -196,6 +196,7 @@ pub fn create_themed_visuals(theme: ColorTheme, default: Visuals) -> Visuals {
             width: 1.0,
             color: theme.window_stroke_color,
         },
+        image_loading_spinners: false,
         ..default
     }
 }