The CustomProperty class currently only [supports](https://github.com/PyGithub/PyGithub/blob/main/github/OrganizationCustomProperty.py#L51) ["string", "single_select"]. GitHub now [supports](https://docs.github.com/en/rest/orgs/custom-properties?apiVersion=2022-11-28#create-or-update-custom-properties-for-an-organization) multi_select and true_false in addition to these.