Changelog and Full Release in the same workflow

[jtpio]

Problem

To push the automation even further, maybe there could be an additional workflow that would create the new changelog entry and do the full release right after?

The changelog entry would be added as a single commit, and the next commit would be the publish commit.

This would slightly change the current workflow of having the changelog entry added as a PR.

Proposed Solution

Probably folks can already do that with the jupyter_releaser CLI already, and that workflow could even live in their repo directly.

So we could either document such workflow, or add it to the releaser repo like the existing ones.

Additional context

cc @martinRenou who was interested in this

[jtpio]

Linking to #272 as related.