fix(dav): fix event birthday alarms not being updated

In #33251 the default offset for
a birthday event alarm was changed to 9AM on the day of the event.

However the birthdayEvenChanged method did not account for alarm
changes, so it was never propagated to existing birthday events, which
were kept on midnight.

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

apps/dav/lib/CalDAV/BirthdayService.php

@@ -317,6 +317,11 @@ public function syncUser(string $user):void {
 	}
 
 	/**
+	 * The birthday event is considered changed if either
+	 *  - the start date has changed
+	 *  - the title has changed
+	 *  - the time for the alarm has changed
+	 *
 	 * @param string $existingCalendarData
 	 * @param VCalendar $newCalendarData
 	 * @return bool
@@ -331,7 +336,8 @@ public function birthdayEvenChanged(string $existingCalendarData,
 
 		return (
 			$newCalendarData->VEVENT->DTSTART->getValue() !== $existingBirthday->VEVENT->DTSTART->getValue() ||
-			$newCalendarData->VEVENT->SUMMARY->getValue() !== $existingBirthday->VEVENT->SUMMARY->getValue()
+			$newCalendarData->VEVENT->SUMMARY->getValue() !== $existingBirthday->VEVENT->SUMMARY->getValue() ||
+			($newCalendarData->VEVENT->VALARM && $existingBirthday->VEVENT->VALARM && $newCalendarData->VEVENT->VALARM->TRIGGER->getValue() !== $existingBirthday->VEVENT->VALARM->TRIGGER->getValue())
 		);
 	}