Upgrade fontawesome v5 to v6

public_html/pages/error_404.php

 <?php
     header("HTTP/1.0 404 Not Found");
 ?>
-<h1><i class="fas fa-exclamation-triangle"></i> 404 :: page not found</h1>
+<h1><i class="fa-solid fa-exclamation-triangle"></i> 404 :: page not found</h1>
 <p>
 
 </p>
\ No newline at end of file