[CORE] Fix 'Array and string offset access syntax with curly braces is deprecated' in AuthCryptModule and DirectionDetectorPlugin

plugins/DirectionDetector/DirectionDetectorPlugin.php

@@ -143,7 +143,7 @@ class DirectionDetectorPlugin extends Plugin {
         $len = strlen($str);
 
         for($i = 0; $i < $len; $i++) {
-            $in = ord($str{$i});
+            $in = ord($str[$i]);
             if (0 == $mState) {
                 // When mState is zero we expect either a US-ASCII character or a
                 // multi-octet sequence.