[core] Calculate date by strftime_or_none; fix seconds in datetime_round

- Negative datetime is not acceptable on Windows.
- Scale the timestamp up 1000000 times to calculate milliseconds.

yt_dlp/YoutubeDL.py

@@ -2673,11 +2673,7 @@ class YoutubeDL:
                 ('modified_timestamp', 'modified_date'),
         ):
             if info_dict.get(date_key) is None and info_dict.get(ts_key) is not None:
-                # Working around out-of-range timestamp values (e.g. negative ones on Windows,
-                # see http://bugs.python.org/issue1646728)
-                with contextlib.suppress(ValueError, OverflowError, OSError):
-                    upload_date = dt.datetime.fromtimestamp(info_dict[ts_key], dt.timezone.utc)
-                    info_dict[date_key] = upload_date.strftime('%Y%m%d')
+                info_dict[date_key] = strftime_or_none(info_dict[ts_key])
 
         if not info_dict.get('release_year'):
             info_dict['release_year'] = traverse_obj(info_dict, ('release_date', {lambda x: int(x[:4])}))