flake8-string-format fails with Python 3.14

[xqt]

flake8-string-format fails with Pythonn 3.14 due to Removal of ast.Num, ast.Str, ast.Bytes, ast.NameConstant and ast.Ellipsis., see python/cpython#119562

Traceback:
https://github.com/wikimedia/pywikibot/actions/runs/9725654092/job/26843242475

[jonyscathe]

All that needs to change is:

        typ = (ast.Str,)
        if sys.version_info[0] > 2:
            typ += (ast.Bytes,)

to

        typ = (ast.Constant,)

within flake8_string_format.py

I would make a PR, but since there have been no tags for 5 years... I'm doubt it'd actually be merged and released.

[xqt]

I dropped its usage with https://gerrit.wikimedia.org/r/c/pywikibot/core/+/1051780