CVE-2019-16276 Upgrade Concourse to 5.5.3

During today, we’ll roll out Concourse version 5.5.3 to all our setups.

This is a Security patch using GoLang v1.13.1 that address a recently reported issue with Go net/http (CVE-2019-16276).

This upgrade will not require a rotation of the workers so only the web part will require an updte

You can check out the full Concourse changelog here.