Compatability with `datetime.astimezone()`

[tahaum]

Experiencing something similar to what's mentioned in #472:

import datetime
now = datetime.datetime.now(datetime.timezone.utc)
now.astimezone().tzinfo

Outputs: datetime.timezone(datetime.timedelta(seconds=7200), 'CEST')

But:

import freezegun
with freezegun.freeze_time("2025-04-01T00:00"):
    frozen_now = datetime.datetime.now(datetime.timezone.utc)
frozen_now.astimezone().tzinfo

Outputs: tzlocal()

I would expect the behaviour to be equal here.

Edit: The reason we stumbled across this was attempting to do now.astimezone().tzinfo.tzname(None). When using freezegun this fails with the following traceback:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File ".venv/lib/python3.12/site-packages/dateutil/tz/tz.py", line 238, in tzname
    return self._tznames[self._isdst(dt)]
                         ^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/dateutil/tz/tz.py", line 291, in _isdst
    dstval = self._naive_is_dst(dt)
             ^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/dateutil/tz/tz.py", line 259, in _naive_is_dst
    timestamp = _datetime_to_timestamp(dt)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/dateutil/tz/tz.py", line 1814, in _datetime_to_timestamp
    return (dt.replace(tzinfo=None) - EPOCH).total_seconds()
            ^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'replace'