muster release v5.43.3

muster auth login reports why it cannot reach the server instead of a missing challenge. Against a server whose TLS certificate the host does not trust, or one that refuses the connection, the sign-in failed with no auth challenge available, hiding the x509 or connection error. The discovery probe now keeps the error of a request that got no response, and the login and --force re-login report it (cannot reach <endpoint>: … x509: certificate signed by unknown authority). A server that answers without a challenge still reports no auth challenge available. (#1527)