Find automated way to bump a crate's patchlevel _without_ updating its dependents

As part of our release process we sometimes need to bump a crate's patchlevel but not update the version of that crate which other crates depend on. This happens when we have changes in the crate that do not affect its behavior, such as new clippy warnings, or revised documentation.

Right now, I have to do this by hand since I don't think it's something that set-version provides. We should be able to write a tool to do this for us easily; however, we should also check whether one exists, or if set-version can be made to do it.