PHP 8.1 support

When logging psalm logs to xml. its gets the following error: 

```
Uncaught RuntimeException: PHP Error: DOMDocument::createTextNode(): Passing null to parameter #1 ($data) of type string is deprecated in /app/vendor/openlss/lib-array2xml/LSS/Array2XML.php:174 in /app/vendor/vimeo/psalm/src/Psalm/Internal/ErrorHandler.php:66
```

in PHP8.1 you cant pass a parameter anymore