MDL-70301 lib: Upgrade scssphp to 1.4.1

lib/scssphp/Exception/ServerException.php

@@ -1,8 +1,9 @@
 <?php
+
 /**
  * SCSSPHP
  *
- * @copyright 2012-2019 Leaf Corcoran
+ * @copyright 2012-2020 Leaf Corcoran
  *
  * @license http://opensource.org/licenses/MIT MIT
  *
@@ -16,6 +17,6 @@ namespace ScssPhp\ScssPhp\Exception;
  *
  * @author Anthon Pang <[email protected]>
  */
-class ServerException extends \Exception
+class ServerException extends \Exception implements SassException
 {
 }