Add `TimeTuple = Tuple[int, int, int, int, int, int, int, int, int]`
to stdlib/3/time.pyi and stdlib/3/datetime.pyi.
Use `TimeTuple` instead of `tuple` (where relevant) in time.pyi for
stronger type checking.
Use `TimeTuple` instead of
`Tuple[int, int, int, int, int, int, int, int, int]` in datetime.pyi
to increase readability.
timezone inherits from tzinfo, so using tzinfo is more general (and e.g.
pytz types inherit directly from tzinfo).
This is the correct type, as quoted from astimezone's code:
elif not isinstance(tz, tzinfo):
raise TypeError("tz argument must be an instance of tzinfo")
