[issue46266] Improve day constants (`MONDAY` ... `SUNDAY`) in `calendar.py`

[Nikita Sobolev]

Change by Nikita Sobolev <mail at sobolevn.me>:


----------
keywords: +patch
pull_requests: +28618
stage:  -> patch review
pull_request: https://github.com/python/cpython/pull/30412

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue46266>
_______________________________________