[all versions] account_banking_sepa_direct_debit: cron that expires mandates unused for 3 years should only apply to sepa mandates

I found this bug while reading the code: in the module account_banking_sepa_direct_debit, the cron that expires the mandates unused for 36 months should only apply on sepa mandates, not on mandates with format=basic.

The code to fix is located here:
https://github.com/OCA/bank-payment/blob/18.0/account_banking_sepa_direct_debit/models/account_banking_mandate.py#L98