SPACE is not UPOS

Hey,
First of all thanks for the great job!
I am currently using stanza via spaCy for an small annotation projection project. However while integrating I realized that spacy-stanza uses an [custom Universal POS tag](https://github.com/explosion/spacy-stanza/blob/a87c723a1f45b456c3488e13afb0090362016bf9/spacy_stanza/tokenizer.py#L110-L140). I guess its a bit against the idea of [Universal POS tags](https://universaldependencies.org/u/pos/index.html) and it makes my life harder since I need another run to filter those tags out.
My questions are now: Is there any reason why this wrapper does not filter them out? Is there any possible solution/workaround/filter possible to overcome this?
Thanks for your time!