Remove maintain permissions

[VOVELEE]

There is no maintain permission in GitHub permissions. Removing it from code base because it can bring confusion with maintain role.

Official documentation: https://docs.github.com/en/enterprise-cloud@latest/rest/collaborators/collaborators?apiVersion=2022-11-28#get-repository-permissions-for-a-user

Checks the repository permission of a collaborator. The possible repository permissions are admin, write, read, and none.

Note: The permission attribute provides the legacy base roles of admin, write, read, and none, where the maintain role is mapped to write and the triage role is mapped to read. To determine the role assigned to the collaborator, see the role_name attribute, which will provide the full role name, including custom roles. The permissions hash can also be used to determine which base level of access the collaborator has to the repository.