pytest needed as extra dependency when using ro-crate-validator-py

[kinow]

From the WIP PR: https://github.com/ResearchObject/runcrate/pull/17/files#diff-fa602a8a75dc9dcc92261bac5f533c2a85e34fcceaff63b3a3a81d9acde2fc52R45

Probably because of a loose import in this module (there could be others): https://github.com/ResearchObject/ro-crate-validator-py/blob/main/src/rocrateValidator/semanticCheck.py#L11

[stain]

Thanks, @kinow!

@Logan-174 Are you able to give me access to https://pypi.org/project/rocrateValidator/ so I can make another release? username stain