Calendar notifications are sent at whatever time

### What Happened?

I added a Gmail calendar to a fresh Elementary 6.1 install and the calendar app ~~never triggers any notification.~~ triggers notifications at whatever time.

- All my events are setup with a notification 10 minutes before the event.
- I can see the notification listed in the events' details in the Calendar app.
- Notifications are enabled for the Calendar app —it's even the only app allowed to play a sound!
- The background service is running (`io.elementary.calendar --background`).
- Sometimes the Calendar app is also running.
- Last but not least: notifications are working (other apps do trigger notifications, e.g. Slack, Geary) and I'm not in "do not disturb" mode.

In Elementary 5, the calendar was sending notifications at whatever time before or after (sigh), and I hoped that it would be finally fixed in Elementary 6 :face_exhaling:

### Steps to Reproduce

See above.

### Expected Behavior

I should receive notifications for my calendar events, just as scheduled **and on time** in regards to Timezone and Daylight Saving Time (DST).

Scenario:

- my event is scheduled at 15:30 with a notification set to 10 minutes _before_;
- my timezone is Europe/Paris (CEST with DST on 2022-10-21)
- I expect to be notified at 15:20 CEST (13:20 UTC), not at 16:25 CEST (14:25 UTC) or 55 minutes _after_ the event.

### OS Version

6.x (Odin)

### Software Version

Latest release (I have run all updates)

### Log Output

_No response_

### Hardware Info

_No response_