`tz` field is technical field related to `resource_id`, which is required field on that model. However it is possible to try to write a void value, which leads to an issue as it is technically required. With this commit we make the tz field required at write. closes odoo/odoo#77372 X-original-commit: 7cda3632b1f50ea757d25369e8a1261d8aeab16d Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>