message: Improve error message on azure auth not being supported
  be more explicit on azure auth not being supported
diff: @@ -324,6 +324,9 @@ fn token_from_provider(provider: &AuthProviderConfig) -> Result<ProviderToken, E
  match provider.name.as_ref() {
  "oidc" => token_from_oidc_provider(provider),
  "gcp" => token_from_gcp_provider(provider),
  + "azure" => Err(Error::AuthExec(
  + "The azure auth plugin is not supported; use https://github.com/Azure/kubelogin instead".into()
  + )),
  _ => Err(Error::AuthExec(format!(
  "Authentication with provider {:} not supported",
  provider.name
  