Fix error with tuple assignation in contract mobile change tariff wizard
CHANGELOG:
### Fixed
- [#967](https://git.coopdevs.org/coopdevs/som-connexio/odoo-somconnexio/-/merge_requests/967) Fix 'fiber_linked' parameter assignation in ContractMobileTariffChangeWizard
Related card: https://trello.com/c/hQHsLoW4/1533-error-canvi-de-tarifa-m%C3%B2bil-a-producte-pack
Edited by Gerard Funosas