Use replace(tzinfo) to adopt the remind timezone

The _localtz option should serve as an override, to add the timezone of
the Remind event, so replace() is correct. astimezone() instead would
shift the event date from the system timezone to _localtz.

Fixes a regression in 2c41e72.

remind.py

@@ -131,7 +131,7 @@ def _parse_remind(
                 if "eventstart" in entry:
                     dtstart: datetime | date = datetime.strptime(
                         entry["eventstart"], "%Y-%m-%dT%H:%M"
-                    ).astimezone(self._localtz)
+                    ).replace(tzinfo=self._localtz)
                 else:
                     dtstart = datetime.strptime(entry["date"], "%Y-%m-%d").date()