python/cpython#132323 added new arguments to the default HelpFormatter which are conditionally called in Python 3.14. The subclass neither accept additional arguments nor passes these along which causes an error, see python/cpython#132323 (comment).

/CC @asottile

Thanks for contributing, make sure you address all the checklists (for details on how see development documentation)

• ran the linter to address style issues (tox -e fix)
• wrote descriptive pull request text
• ensured there are test(s) validating the fix
• added news fragment in docs/changelog folder
• updated/extended the documentation