EscapingFunctionsTrait: add wp_timezone_choice() to the list of auto-escaped functions

This function was introduced in WP 2.9.0.

I've looked the code of the function over and agree it can be added to the auto-escaped functions list.

Ref: https://developer.wordpress.org/reference/functions/wp_timezone_choice/

Fixes 1904

Author: jrfnl

WordPress/Helpers/EscapingFunctionsTrait.php

@@ -164,6 +164,7 @@ trait EscapingFunctionsTrait {
 		'wp_nav_menu'               => true,
 		'wp_register'               => true,
 		'wp_tag_cloud'              => true,
+		'wp_timezone_choice'        => true,
 		'wp_title'                  => true,
 	);