[IMP] hr_holidays: show correct week number in year calendar view

Currently in time off, we show the year view of calendar with the configuration
that shows the week number beside each week row. However, it starts as week 52.
This is a bug in fullcalendar that should be fixed by setting the option
firstDay as 0, according to this issue
https://github.com/fullcalendar/fullcalendar/issues/7026.

task-3455051

Part-of: odoo/odoo#138670

addons/hr_holidays/static/src/views/calendar/year/calendar_year_renderer.js

@@ -44,6 +44,7 @@ export class TimeOffCalendarYearRenderer extends CalendarYearRenderer {
             weekNumbers: true,
             weekNumbersWithinDays: false,
             weekLabel: _t("Week"),
+            firstDay: 0,
         });
     }