worker/awsCertlint: add os/exec timeout
worker/awsCertlint: add os/exec timeout

mozilla/tls-observatory,jasonthomas/tls-observatory,mozilla/tls-observatory,jasonthomas/tls-observatory,mozilla/tls-observatory,mozilla/tls-observatory,jasonthomas/tls-observatory,mozilla/tls-observatory,mozilla/TLS-Observer,jasonthomas/tls-observatory,jasonthomas/tls-observatory