Force-load fSelect

<?php

add_filter( 'facetwp_load_assets', '__return_true' );

add_filter( 'facetwp_assets', function( $assets ) {
    $assets['fSelect.js'] = FACETWP_URL . '/assets/vendor/fSelect/fSelect.js';
    $assets['fSelect.css'] = FACETWP_URL . '/assets/vendor/fSelect/fSelect.css';
    return $assets;
});