DateOffset for weekday argument requires weekday argument from dateutil

[Dr-Irv]

The issue is that the type specification for the weekday argument in pandas-stubs/_libs/tslibs/offsets.pyi says that weekday is an int. But it can be a weekday class or an int. See https://dateutil.readthedocs.io/en/stable/relativedelta.html To fix this, we have to make types-python-dateutil a dependency, which involves modifying pyproject.toml and takes some care.

Created a docs issue for pandas at pandas-dev/pandas#52650

Originally posted by @Dr-Irv in #645 (comment)

[twoertwein]

In quite a few cases, the code seems to explicitly test that weekday is between 0 and 6 (WeekOfMonthMixin, Week, WeekOfMonth).

[loicdiridollou]

In quite a few cases, the code seems to explicitly test that weekday is between 0 and 6 (WeekOfMonthMixin, Week, WeekOfMonth).

For the other ones you mentioned, there is a type check at the __init__ so you can only pass a weekday class from dateutil.relativedelta in pd.DateOffset. Let me know if I missed anything!