fix token as array on DowngradeDereferenceableOperationRector

Author: samsonasik

rules/DowngradePhp80/Rector/ArrayDimFetch/DowngradeDereferenceableOperationRector.php

@@ -98,7 +98,7 @@ private function hasParentheses(ArrayDimFetch $arrayDimFetch): bool
                 continue;
             }
 
-            if ($oldTokens[$i] !== ')') {
+            if ((string) $oldTokens[$i] !== ')') {
                 continue;
             }