function slick_cdn_enqueue_scripts(){
    wp_enqueue_style( 'slick-style', '//cdn.jsdelivr.net/npm/slick-carousel@1.8.1/slick/slick.css' );
    wp_enqueue_script( 'slick-script', '//cdn.jsdelivr.net/npm/slick-carousel@1.8.1/slick/slick.min.js', array(), null, true );
}
add_action( 'wp_enqueue_scripts', 'slick_cdn_enqueue_scripts' );