fleshed out "nightly builds" system

[Gankra]

A couple releases ago we shipped an undocumented feature called release-branch:

https://github.com/axodotdev/cargo-dist/blob/d97fc68880d963781aec462c72cd2c58cd3d142c/cargo-dist/src/config.rs#L245-L247

This feature is for a gitops-style "every push to this branch is a deploy". As part of this we force cargo-dist to select all publishable apps, take the maximum of their versions, and then append -alpha.{timestamp} to that version, and then pretend the all apps have that version:

https://github.com/axodotdev/cargo-dist/blob/d97fc68880d963781aec462c72cd2c58cd3d142c/cargo-dist/src/announce.rs#L511-L525

A lot of this is the machinery you might want for a "nightly release" but there are some potential differences/improvement:

• The cargo packages aren't actually modified to have the given version (so clap-based --version flags won't mention it's a nightly)
  • While in a concrete case this is straight-forward, in the general case things are quite complicated with things like workspace-version-inheritance. I briefly looked into vendoring some code from release-plz but ended up discarding it when i got to the end.
  • If you care about commiting and tagging your nightlies this raises a lot of questions about modifying the tree permanently
• For a "nightly" workflow you might want something more akin to a cron job than "every push"
• As seen in the comments, it would be nice for the version string to be a template

[Dekker1]

This was a feature that I was looking for! When trying it by setting release_branch in Cargo.toml it, however, seems to fully replace the mechanism of releasing based on tags when looking at the newly generated action. For my purpose I'm happy with the currently described mechanisms, but I would still want to also create "final" releases. Am I overlooking a way in which this is still possible, or would additional engineering be required to also allow the normal release mechanism?