Automated the generation of changelogs in text format

[soham30rane]

Associated with #480 on website repo

This pull request defines a workflow which is executed when any release is published.
It in turn triggers the execution of Generate Changelog workflow in website repo and the changelog is generated in .txt format if the current release was a stable release.

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

[github-actions]

Documentation preview for this PR (built with commit 72d1e6d; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[kwankyu]

This PR is complemented by #39083.

[kwankyu]

It seems that the workflow is not triggered by a release.

[kwankyu]

I expected that the workflow itself runs but the steps are skipped for pre-releases.

Of course, it is okay that the workflow does not run for pre-releases. Let's wait and see what happens for a stable release.

[soham30rane]

Yes, ideally the workflow should have run and the steps should have been skipped

[kwankyu]

The workflow https://github.com/sagemath/sage/actions/workflows/changelog_trigger.yml does not run even for a stable release...

[kwankyu]

Perhaps

on:
  release:
    types: [created]

would work?

[soham30rane]

My LLM also suggested something similar.
Interestingly though, when I tested the same logic in my test repo, it did trigger correctly with types: [published], even though the release was created in the same way (via the curl API with draft=false) as in this repo.

GitHub’s behavior around this seems a bit flaky, so I’m all for trying types: [created].
If that still doesn’t fire, we can use workflow_run and trigger it after dist.yml finishes.

[kwankyu]

My LLM also suggested something similar. Interestingly though, when I tested the same logic in my test repo, it did trigger correctly with types: [published], even though the release was created in the same way (via the curl API with draft=false) as in this repo.

Yes. Though I don't remember clearly, I must have also tested it successfully on my own repo. Strange..

GitHub’s behavior around this seems a bit flaky, so I’m all for trying types: [created]. If that still doesn’t fire, we can use workflow_run and trigger it after dist.yml finishes.

Thanks for the tips. Let's pass one more release with types: [published].

If that fails, we pass the next release with types: [created].

If that still fails, we use workflow_run.

Let's see. Thanks.

[kwankyu]

I just found why the workflow does not run on a new release.

https://docs.github.com/en/actions/how-tos/write-workflows/choose-when-workflows-run/trigger-a-workflow#triggering-a-workflow-from-a-workflow

To summarize: because the release (event) is made by a workflow with GITHUB_TOKEN, the release event does not trigger another workflow (to prevent accidental infinite loop).

The article also tells a solution. I will prepare a PR soon.