[#268] changed timezone offset calculation (#306)

Co-authored-by: Camille Moussu <cmoussu@linagora.com>

src/components/Calendar/Calendar.tsx

@@ -407,6 +407,7 @@ export default function CalendarApp({
                 </div>
                 <TimezoneSelector
                   value={timezone}
+                  referenceDate={calendarRef.current?.getDate() ?? new Date()}
                   onChange={(newTimezone: string) =>
                     dispatch(setTimeZone(newTimezone))
                   }