GMS-2023-493: vantage6 vulnerable to Improper Preservation of Permissions

vantage6 is a privacy preserving federated learning infrastructure for secure insight exchange. Assigning existing users to a different organizations is currently possible. It may lead to unintended access: if a user from organization A is accidentally assigned to organization B, they will retain their permissions and therefore might be able to access stuff they should not be allowed to access. This issue is patched in version 3.8.0.