Add button-hero for site icon so styles match customizer

Author: joedolson

src/wp-admin/options-general.php

@@ -105,7 +105,7 @@
 	wp_enqueue_media();
 	wp_enqueue_script( 'site-icon' );
 
-	$classes_for_upload_button = 'upload-button button';
+	$classes_for_upload_button = 'upload-button button-hero button';
 	$classes_for_update_button = 'button';
 	$classes_for_wrapper       = '';