Use our own container for CI

Currently deployments fail at this point:

which rsync || ( apt-get update -qq && apt-get install rsync -yqq )
W: GPG error: http://security.debian.org/debian-security buster/updates InRelease: At least one invalid signature was encountered.
E: The repository 'http://security.debian.org/debian-security buster/updates InRelease' is not signed.
W: GPG error: http://deb.debian.org/debian buster InRelease: At least one invalid signature was encountered.
E: The repository 'http://deb.debian.org/debian buster InRelease' is not signed.
W: GPG error: http://deb.debian.org/debian buster-updates InRelease: At least one invalid signature was encountered.
E: The repository 'http://deb.debian.org/debian buster-updates InRelease' is not signed.

I believe this is because an old image is being used, ruby:2.6.6, it would be better if we built our own container rather than using an external one, I'll see if I can use this one.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information