[COMPOSER] update

vendor/ezyang/htmlpurifier/library/HTMLPurifier/Encoder.php

@@ -159,7 +159,7 @@ class HTMLPurifier_Encoder
 
         $len = strlen($str);
         for ($i = 0; $i < $len; $i++) {
-            $in = ord($str{$i});
+            $in = ord($str[$i]);
             $char .= $str[$i]; // append byte to char
             if (0 == $mState) {
                 // When mState is zero we expect either a US-ASCII character