[FIX] hr_work_entry_contract: fix the traceback when we edit multiple contract's Working Schedule

Reproduction steps:
 -Install payroll app
- Got to payroll > Contracts > Contracts > List view
- Select multiple record and modify the Working Schedule

- missing return in write

closes odoo/odoo#115105

X-original-commit: fcbff003ccc4cfda48b5b266929ee49f6ace3523
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/hr_work_entry_contract/models/hr_contract.py

@@ -388,8 +388,8 @@ class HrContract(models.Model):
         dependendant_fields = self._get_fields_that_recompute_we()
         if any(key in dependendant_fields for key in vals.keys()):
             for contract in self:
-                date_from = max(self.date_start, self.date_generated_from.date())
-                date_to = min(self.date_end or date.max, self.date_generated_to.date())
+                date_from = max(contract.date_start, contract.date_generated_from.date())
+                date_to = min(contract.date_end or date.max, contract.date_generated_to.date())
                 if date_from != date_to:
                     contract._recompute_work_entries(date_from, date_to)
         return result