fix for towncrier>=24.7.0

[bjlittle]

This pull-request updates sphinx-changelog to work with towncrier>=24.7.0.

As sphinx-changelog uses private towncrier functions it's liable to break for minor releases.

In this case the signature of towncrier._builder.find_fragments changed under-the-hood, which was the source of the issue.

Note that, towncrier is also now a little bit richer and can traverse up directory trees to find the configuration file and also has better base_directory management, and so some of the defensive code within sphinx-changelog melts away.

I've tested this pull-request change against building my own project, and renders its changelog as expected 👍

I also built the sphinx-changelog docs and checked the test_changelogs page, which appears to render fine.

I guess you want to ensure these changes are compatible with your own projects.

[bjlittle]

I've set strict=False here to ensure the same sphinx-changelog behaviour.

If we opt to set this to True then users may have to explicitly include their template file to the configured ignore files.

[Cadair]

Thank you very much for doing this. I think this looks good I shall merge it and then do an rc release for wider testing.

[Cadair]

1.6.0rc1 is out, I have opened sunpy/sunpy#7787 and astropy/astropy#16883 for testing. If you have any other things you want to test with the rc please let me know how it goes :)

[bjlittle]

@Cadair Thanks for pushing this through, very much appreciated 🍻

There isn't any further testing that I personally want to make.

As an aside, if it helps, I'm happy to be a maintainer and crank the handle over on https://github.com/conda-forge/sphinx_changelog-feedstock, as I tend to mainly pull packages from conda-forge rather than pypi.

So I'm keen to keep the conda-forge channel in sync with the latest package release on PyPI.

[Cadair]

I shall publish the final release tomorrow then. I have added you to the feedstock