Replace Month enum with builtin calendar.Month

[lemonyte]

sir-robin/bot/constants.py

Lines 112 to 117 in 1a67d49

	class Month(enum.IntEnum):
	"""
	Enum lookup between Months & month numbers.
	Can bre replaced with the below when upgrading to 3.12
	https://docs.python.org/3/library/calendar.html#calendar.Month

According to pyproject.toml the minimum Python version is now 3.14.

sir-robin/pyproject.toml

Line 5 in 1a67d49

requires-python = "==3.14.*"