Windows datetime.astimezone(tz=None) should return tzinfo with zone name that can be used by ZoneInfo

[tjwilli58]

Bug report

Bug description:

I often use datetime.astimezone() to make my datetime objects tz-aware. Using astimezone(tz=None) is very convenient, but the tzinfo object that is returned has a tzname() that can't be passed to ZoneInfo:

import datetime
from zoneinfo import ZoneInfo

dt=datetime.datetime.now().astimezone()
dt.tzname()
'Eastern Standard Time'

If I try

ZoneInfo(dt.tzname())

I get
ZoneInfoNotFoundError: 'No time zone found with key Eastern Standard Time'

I understand why, and I almost submitted this issue for zoneinfo, but after looking at the docs, I thought it would be more appropriate for the datetime module.

What I've done recently is to create a dictionary to map the timezones to something ZoneInfo has a key for:

US_timezone_dict = {'eastern standard time':'US/Eastern',
                    'eastern daylight time':'US/Eastern',
                    'central standard time':'US/Central',
                    'central daylight time':'US/Central',
                    'mountain standard time':'US/Mountain',
                    'mountain daylight time':'US/Mountain',
                    'us mountain standard time':'US/Arizona',
                    'pacific standard time':'US/Pacific',
                    'pacific daylight time':'US/Pacific',
                    'alaska standard time':'US/Alaska',
                    'aleutian standard time':'US/Aleutian',
                    'hawaiian standard time':'US/Hawaii',
                    }
_timezone = dt.tzname()
if _timezone and _timezone.lower() in US_timezone_dict:
    _timezone = US_timezone_dict[_timezone.lower()]

Now this works for me, but it would be nice is dt.astimezone() would return a tzinfo with a name that ZoneInfo knows about.

I can do

dt=datetime.datetime.now().astimezone(ZoneInfo('US/Eastern'))
dt.tzname()
Out[32]: 'EST'

but I don't always know which time zone I will be in when I run my code.
Thanks.

CPython versions tested on:

3.11

Operating systems tested on:

Windows