Poor man's CSS cache busting in WP

CSS_cache_busting_WP.php

<?php
function wp_scripts() {
  //Internal cache tracking
  wp_enqueue_style( 'theme-style', get_stylesheet_directory_uri() . '/style.css', array(), filemtime( get_stylesheet_directory() .'/style.css' ), 'all' );
  //External cache tracking
  wp_enqueue_style( 'global-styles', 'https://example-assets.com/css/global_styles.css', array(), strtotime( wp_remote_retrieve_header( wp_remote_get( 'https://example-assets.com/css/global_styles.css'), 'last-modified' ) ) );
}
?>