devel/py-validictory: limit supported python versions

File "/wrkdirs/usr/ports/devel/py-validictory/work-py310/validictory-1.1.2/validictory/validator.py", line 7, in <module>
  from collections import Mapping, Container

ImportError: cannot import name 'Mapping' from 'collections' (/usr/local/lib/python3.10/collections/__init__.py)

Approved by: portmgr blanket