chore: towncrier workflow to trigger changelog build

[ThibaultFy]

Summary

Part of converting auto release script into Python, we need a Github action to be triggered with python to create and edit the changelog.

This workflow is dispatch only, and commit the changes directly to the branch.

To be tested on SubstraFL and to propagate to all repo if the test is a success.

See https://github.com/Substra/substrafl/actions/runs/9698562413 for a successful run

Notes

Please check if the PR fulfills these requirements

• If the feature has an impact on the user experience, the changelog has been updated
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• The commit message follows the conventional commit specification

[SdgJlbl]

I'm not sure to have enough context to understand why we need a separate github action for that.
Would this workflow then be called by gh during the release script?

[ThibaultFy]

I'm not sure to have enough context to understand why we need a separate github action for that. Would this workflow then be called by gh during the release script?

Yes the context is quite hard to explain... I'm trying to do a fully distant release proces. The idea is to avoid to have to clone the repo and ensure you have to changes etc... The idea would be to trigger this workflow with the PyGithub API (equivalent to gh) as you said. And the towncrier step is a "non github step" so the only way I found to be able to run it through a github command is creating a workflow... Happy to discuss it if you have any suggestion !