Remove screen_icon() from Options Framework options page

screen_icon and get_screen_icon are deprecated since WordPress 4.8.

screen_icon() triggers a _deprecated_function() call and calls
get_screen_icon(), which outputs an HTML comment:
https://developer.wordpress.org/reference/functions/get_screen_icon/

lib/options-framework/options-framework.php

@@ -229,7 +229,6 @@ function optionsframework_page() {
  settings_errors(); ?>
 
  <div id="optionsframework-wrap" class="wrap">
- <?php screen_icon( 'themes' ); ?>
  <h2 class="nav-tab-wrapper">
  <?php echo optionsframework_tabs(); ?>
  </h2>