Fix depreciation warning for positional args for login spec

Issue: gitlab.com/gitlab-org/gitlab/-/issues/258994

spec/support/helpers/login_helpers.rb

@@ -198,7 +198,7 @@ module LoginHelpers
     env['omniauth.error.strategy'] = strategy
   end
 
-  def stub_omniauth_saml_config(messages, context: Rails.application)
+  def stub_omniauth_saml_config(context: Rails.application, **messages)
     set_devise_mapping(context: context)
     routes = Rails.application.routes
     routes.disable_clear_and_finalize = true