Study reno and investigate improvements to the release process #10110
Description
As emerges from #10104, we use reno for release notes aggregation but we don't have a deep understanding of how the tool works.
This results in a release process that does not work very well with reno.
While we found a workaround for most pressing issues in #10107, it would be better to acquire full control of this tool.
This might be difficult due to poor reno documentation and limited examples.
Plus, reworking the release process to make it fully compatible with reno could involve dealing with previous git history.
Based on a first quick analysis, there don't seem to be alternative tools that we can adopt without significant effort.