add a bump version command

[RonnyPfannschmidt]

there should be a builtin command that enables to create actual tags it should solve the simple use-case, and perhaps provide connected tooling for a more complex use-case

[jaraco]

How would you imagine this command would work? Something like how bumpversion works, except under setup.py but presumably without re-writing any files (only handling tags)?

[RonnyPfannschmidt]

@jaraco the idea is to provide a command that only creates a tag and maybe pushes it

the main idea is to ease creating signed/annotated tags

[nolar]

At least, the next major/minor/micro/rc/dev version should be calculated and printed to stdout.

Some CI/CD tools do not have the permissions to push to the git repos from the build environments, but they can provide the workarounds on how to create the tags/releases: e.g. on GitHub[Enterprise] via the API calls. For this, we have to call these tools with the "next release version" to be created. Calculating it in the shell can be painful.

If at least this is available, people can put the tags themselves: e.g. git tag $(./setup.py --next-minor-version), and push them as needed.

[webknjaz]

Linking related issues:

• https://github.com/pypa/setuptools_scm/issues/455
• https://github.com/pypa/setuptools_scm/issues/773