Staxmate indentation not work with woodstox 2.7.0

The indentation does not work as expected when using staxmate with the last version of woodstox, 7.2.0. It is is added before the closing > if child elements are used.

See [here](https://github.com/FasterXML/woodstox/issues/290#issuecomment-4578076889), the proposed fix ist to keep the change in woodstox and make small modification in staxmate so that it adds a blank to enforce writing the close tag.