Bump system version to 1.0.4

[iliana]

In preparation for the next release, bump the system version.

[iliana]

I realized a few hours ago that this change does have the effect of also bumping all our control plane component versions to "4.0.0". This is probably not ideal.

I might prefer to change this to keep the version stamped into zones and whatnot at the current version, and replace the system version in the tuf-repo.sh job.

[askfongjojo]

How about we make it v1.0.4 first? It should not result in confusion as long as we are good about linking this to the marketing version in our internal documentation.

[iliana]

As in, control plane components versioned v1.0.4, while still adjusting the system version to v4.0.0?

[askfongjojo]

Sorry for being unclear. Just bumping the system version to 1.0.4, exactly like how we did it for 1.0.3.

[iliana]

OK. I'll adjust this PR and we'll work out the finer details.

Content removed from repo description

It is my understanding that we're now describing system versions to customers as integers, but the system_version field we have across the control plane is a SemverVersion, which means current software is going to continue expecting a semver unless/until we change that.

It is simple enough to convert an integer version to semver (just add .0.0!™), and we can still trivially stamp the commit hash into our CI-generated repos as we do now. Future release engineering work will replace the system version with a non-CI-stamped one when signing updates.

[askfongjojo]

For the record - LGTM after all the back-and-forth.