* [mypy] Fixes typing errors in other/date_to_weekday
* [mypy] uses future annotation style for other/date_to_weekly
* date_to_weekday: new implementation replaces buggy original
* date_to_weekday: add examples from multiple of 100 years
* clean-up: runs `black` to fix formatting
* Delete date_to_weekday.py
Co-authored-by: Christian Clauss <cclauss@me.com>