Prevent PHP notice with non-string property names

Author: jissereitsma

Filter/Security.php

@@ -43,7 +43,7 @@ private function allowStripTags(string $value, FilterScope $scope): bool
             return true;
         }
 
-        $field = $this->getFieldByPropertyName($repository, $property);
+        $field = $this->getFieldByPropertyName($repository, (string)$property);
         if (empty($field)) {
             return true;
         }