Issue with Ellipsis in Union typing

[anwai98]

It seems python<3.11 (tested it on 3.10) does not support Ellipsis as an argument in the Union typing (it seems like it cannot derive the class associated for it).

The easy way out solution is to use either type(Ellipsis) or type(...) (however, I feel these are not so elegant solutions). The other thing could be to ensure that users have python>=3.11 installed via the editable install or via conda-forge as well!

What do you think @constantinpape?

[constantinpape]

Fixed in #110