Fixing formatting of logging of objects implementing JsonSerializable…

…: printing unescaped unicode characters.

src/Log/Engine/BaseLog.php

@@ -100,7 +100,7 @@ protected function _format($data, array $context = [])
         }
 
         if ($object && $data instanceof JsonSerializable) {
-            return json_encode($data);
+            return json_encode($data, JSON_UNESCAPED_UNICODE);
         }
 
         return print_r($data, true);