staging.gitlab.com is down

There is an ongoing service interruption for staging.gitlab.com due to the expired SSL certificate.

The corrective actions to take are:

• Renew SSL certificate: https://gitlab.com/gitlab-com/infrastructure/issues/2026
• Create an alert: https://gitlab.com/gitlab-com/infrastructure/issues/2029

Also, what could we do in order to also detect the expiration date for the credit cards we use to purchase the certs? /cc @pcarranza