custom filter change free to wfea__free class

widget-for-eventbrite-api.php

/**
 * Plugin Name:       Display Eventbrite Events - Custom Filters
 * Plugin URI:        https://fullworksplugins.com/products/widget-for-eventbrite/
 * Description:       Custom Filters for Display Eventbrite - changes class of free events
 * Version:           1.0
 * Author:            Fullworks
 * Author URI:        https://fullworksplugins.com/
 * License:           GPL-2.0
 **/
add_filter(
	'wfea_event_classes',
	function ( $classes ) {
		return str_replace( 'free', 'wfea__free', $classes );
	},
	10,
	1
);