Check partner active shares before validate a SR
CHANGELOG:
### Fixed
- [#587](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/587) Check if partner has shares active before validate a SR related with it.
Related card: https://trello.com/c/FNN5XQfa/848-validaci%C3%B3-sr-acceptades
Edited by Pelayo García