[FIX] hr_holidays: compute duration in leave's import

Before this commit, the duration (days/hours of the leave) wasn't
compute when importing leaves.

opw-1916913

closes odoo/odoo#35167

Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>

addons/hr_holidays/models/hr_leave.py

@@ -532,6 +532,8 @@ class HolidaysRequest(models.Model):
         if not values.get('department_id'):
             values.update({'department_id': self.env['hr.employee'].browse(employee_id).department_id.id})
         holiday = super(HolidaysRequest, self.with_context(mail_create_nolog=True, mail_create_nosubscribe=True)).create(values)
+        if self._context.get('import_file'):
+            holiday._onchange_leave_dates()
         if not self._context.get('leave_fast_create'):
             holiday.add_follower(employee_id)
             if 'employee_id' in values: