[FIX] hr_contract: allow employees to read own contract in unusual days

`_get_unusual_days()` does a search for the employee's own contract,
which was not allowed for "simple" employees, thus they got a traceback
when accessing their Time Off Dashboard.

closes odoo/odoo#126946

Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/hr_contract/models/hr_employee.py

@@ -98,7 +98,7 @@ class Employee(models.Model):
         return self.search(['|', ('active', '=', True), ('active', '=', False)])._get_contracts(date_from, date_to, states=states)
 
     def _get_unusual_days(self, date_from, date_to=None):
-        employee_contracts = self.env['hr.contract'].search([
+        employee_contracts = self.env['hr.contract'].sudo().search([
             ('state', '!=', 'cancel'),
             ('employee_id', '=', self.id),
             ('date_start', '<=', date_to),