Convert Date object to datetime with timezone information

[BGWKlein]

A method for HydPy Date objects returning a datetime object with timezone information would be usefull, something like:

from datetime import timezone,timedelta
    
def to_datetime(self, utcoffset: int | None = None) -> datetime:
        """Return a |datetime| object representing the actual date and the eventually given UTC offset (in minutes).

        >>> from hydpy import Date
        >>> date = Date("01.11.1997 00:00:00")
        >>> date.to_datetime()
        datetime.datetime(1997, 11, 1, 0, 0, tzinfo=datetime.timezone(datetime.timedelta(seconds=3600)))

        Passing utcoffset converts the datetime object from the local offset defined by
        |Options.utcoffset| (which defaults to UTC+01:00) to `utcoffset` :

        >>> date.to_datetime(utcoffset=60)
        datetime.datetime(1997, 11, 1, 0, 0, tzinfo=datetime.timezone(datetime.timedelta(seconds=3600)))

        >>> date.to_datetime(utcoffset=0)
        datetime.datetime(1997, 10, 31, 23, 0, tzinfo=datetime.timezone.utc)

        """
        date = self.datetime.replace(tzinfo=timezone(timedelta(minutes=pub.options.utcoffset)))
        
        if utcoffset is not None:
           date = date.astimezone(timezone(timedelta(minutes=utcoffset)))
        return date