RDS CA 2019 cert expires soon/now 22 Aug

[RichardBradley]

The control-tower system includes a copy of AWS's "RDS CA" "2019" cert, which is set to expire on 22 Aug 2024.

This will need updating to the new one. I'm not sure what will break if not. Perhaps everything? Perhaps just fresh installs?
We have updated our RDS to thew new cert directly a few minutes ago and our (running) Concourse hasn't broken yet...

See
#48
and
ee3dbde
from the last time this was needed

The final cert in this file is the one that expires 22 Aug 2024:
https://github.com/EngineerBetter/control-tower/blob/master/db/rds_root_cert.go

[RichardBradley]

Our install stopped working over the weekend, looks it's due to this expired RDS CA cert. The old one is hardcoded in the source.
(I don't know why it took 25 days to fail since the expiry.)

I wouldn't mind trying to fork the project, but I'm not sure how to build and release it (seems to require a Concourse, which is a bit of a circular dependency) or how to update our install to point to my fork.

I've also posted this to concourse/concourse#9002

Any advice would be greatly appreciated