[FIX] google_calendar: Fail silently on 403 response

This happens far too often (daily quota exceded, event
already deleted (?)).
This is a big source of support tickets.
The sync will be retried next time.

Task 2169121

closes odoo/odoo#49401

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