Add a release script

[yannham]

This PR adds a script to automate most of of the releasing process (which is becoming tedious).

The steps covered are:

• Bumping version numbers (including local cross-dependencies, and handling local crates that don't follow the version scheme of the workspace)
• Running checks (nix flake check currently)
• Creating and pushing the release branch, and make the stable branch point to it (after saving the previous stable branch)
• Performing the required pre-processing before publication to crates.io: remove nickel-lang-utils from dependencies, remove the various format features, remove "format" from default features, and remove the dependencies associated to "format"
• Perform checks (--dry-run) and then publish on crates.io

I've tried to inform the user as much as possible, and to gracefully recover in case of error.

This scripts has been tested by parts (commenting out destructive actions like pushing the stable branch or aborting before actually publishing to crates.io), and in different situations manually. I'd still like to get reviews before using it for the 1.4 release, so that I can try the version including review suggestions in real conditions (and avoid having bugs resurfacing when releasing 1.5).

Afterthought

I initially thought I could use tomlq to patch the various Cargo.toml files in place. It's true in theory, but tomlq works by parsing content, transcoding to JSON, using jq for processing, and transcodes back the result to TOML. Needless to say, even if the result is semantically correct, it totally messes up the original formatting and layout of the files, as well as removing all comments, which is unacceptable.

I ended up using sed/awk for modification instead, which is obviously more fragile. Now, if I was to start again, I would consider something like a stand-alone python script (given that there's a library to do what I want, that is localized programmatic modification of TOML). For now this script should be sufficient, but if we need to evolve it in the future, this might be a consideration to keep in mind.

TODO

• re-entrancy once we successfully pushed the x.x.x branch but failed to publish

Future work

• add the script's dependencies to the devshell, (mostly tomlq, beyond basic utilities)

[jneem]

Nice to have this automated!

Did you see if there's anything useful that cargo release has to offer? The topiary stuff probably means we can't just use it out-of-the-box, but for example the cargo release version subcommand might get rid of the version-related sed stuff.

[yannham]

Did you see if there's anything useful that cargo release has to offer?

I haven't looked at it. Thanks for the suggestion, I'll see if it can make some parts of the script simpler!