Optional label text changes

optional_label.php

<?php

add_filter('cartimize_optional_collapse_label_text', 'cartimize_custom_cartimize_optional_collapse_label_text', 10, 2);

function cartimize_custom_cartimize_optional_collapse_label_text($optional_label, $args) {
    $optional_label = esc_html($args['label']);
    $optional_label .= ' '.esc_html__('Add', 'linear-checkout-for-woo-by-cartimize');
    return $optional_label;
}