Check if there's a contract with the ticket number
CHANGELOG:
### ADDED
- [#395](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/395) Checks if there's already a contract with the same ticket number
Edited by Pelayo García
CHANGELOG:
### ADDED
- [#395](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/395) Checks if there's already a contract with the same ticket number