FR: fully automate the release process

[thoughtpolice]

This is mostly for me, I was reminded of it because Martin is doing the 0.11 release, and because I brought it up on Discord a while ago. We should get the release process to be fully automated, not only so that Martin doesn't have to do it, but so that the whole lifecycle is more secure and foolproof.

I think the idea was just to do a release every 4 weeks, on the 1st of every month. This is probably OK for now and we could adjust it in the future depending on how users feel.

There actually isn't that much to do in the grand scheme of things. But breaking it down, we at least need to:

• Tweak CHANGELOG.md automatically
  • We may, frankly, want to just change this process entirely to make it more automation friendly, rather than doing egregious sed hacks or something. Or at least do it right (e.g. an actual markdown parser that can insert changes in the right places.)
• Bump workspace.package.version in Cargo.toml
• Update Cargo.lock with those version changes.
• Commit those changes to main if they build correctly, with a tag
• Have a workflow that creates a release directly from the tag
• Publish to crates.io

There are a lot of finnicky little details to sort out with this, but it can all reasonably be achieved with some elbow grease. In the long run it will drastically simplify things, from setting deprecation deadlines to ensuring continuity.

I'll probably experiment in a separate repository with doing the release of a small rust application. There are in fact some workflows to do this automatically but depending on those things might (or might not!) have their own issues.

[ilyagr]

I can think of two tangentially related issues (neither is a prerequisite for this to work):

• cargo: Change prerelease versions to end in ".1-pre" instead of ".0" #2258 is blocked (at least) on increasing the release workload. If it can be automated, I still think it's a good idea.
• The demos, as discussed in readme: improved front matter, part 2 #2463 (comment), are not currently an issue for automating the release, but would be if we wanted to version them to the "correct" version of jj.