catch overflow error on 32bit platforms

[dirkmueller]

on 32bit platforms the test on large timestamps fails like the following:

 itsdangerous/timed.py:128: in unsign
  ts_dt = self.timestamp_to_datetime(ts_int)
timed.py:47: in timestamp_to_datetime
  return datetime.fromtimestamp(ts, tz=timezone.utc)
 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
 
 cls = <class 'freezegun.api.FakeDatetime'>, t = 21959264258072993
 tz = datetime.timezone.utc
 
     @classmethod
     def fromtimestamp(cls, t, tz=None):
         if tz is None:
             return real_datetime.fromtimestamp(
                     t, tz=dateutil.tz.tzoffset("freezegun", cls._tz_offset())
                 ).replace(tzinfo=None)
 >       return datetime_to_fakedatetime(real_datetime.fromtimestamp(t, tz))
 E       OverflowError: timestamp out of range for platform time_t
 
 /usr/lib/python3.9/site-packages/freezegun/api.py:375: OverflowError

Environment:

• Python version: 3.9 / 32bit
• ItsDangerous version: 2.1.1