tz_offset doesn't work with dateutil.tz #405
Description
datetime.now(UTC) and datetime.utcnow() produce the same output in general, and they both have an offset from datetime.now(). But with freeze_time, datetime.now(UTC) does not have the offset:
datetime.now(): 2021-07-15 15:18:42.491281
datetime.now(UTC): 2021-07-15 20:18:42.491302+00:00
datetime.utcnow(): 2021-07-15 20:18:42.491311
datetime.now(): 2020-01-01 01:00:00
datetime.now(UTC): 2020-01-01 01:00:00+00:00
datetime.utcnow(): 2020-01-01 00:00:00
from datetime import datetime
from dateutil.tz import UTC
from freezegun import freeze_time
print(f'datetime.now(): {datetime.now()}')
print(f'datetime.now(UTC): {datetime.now(UTC)}')
print(f'datetime.utcnow(): {datetime.utcnow()}')
with freeze_time("2020-01-01T00:00:00Z", tz_offset=1):
print(f'datetime.now(): {datetime.now()}')
print(f'datetime.now(UTC): {datetime.now(UTC)}')
print(f'datetime.utcnow(): {datetime.utcnow()}')