Onyxia private helm repository credentials are leaked through unauthenticated API

Onyxia is a data science environment for kubernetes. In versions 4.6.0 through 4.8.0, Onyxia-API leaked the credentials of private helm repositories in the public (unauthenticated) /public/catalogs endpoint.vOnly instances using private helm repositories (i.e setting username & password in the catalogs configuration) are affected. This is fixed in version 4.9.0.