Update algorithm list for snowball 3.1.0

[stefanor]

No description provided.

[ojwb]

Thanks.

I wondered why we weren't running this doctest in CI, and that's was because of some unhelpful backslashes (coupled with python apparently ignoring anything on the command line after --version), which I fixed before merging this, which as expected caused all the jobs to failed: https://github.com/snowballstem/pystemmer/actions/runs/26351785289

I then merged your patch, which fixed builds for python < 3.10 but newer versions fail, apparently because nose is still trying use imp which is gone in newer Python: https://github.com/snowballstem/pystemmer/actions/runs/26351806192

It looks like nose is an inactive project as the last release was 2015: https://pypi.org/project/nose/#history - that would explain why it doesn't know about changes in recent python 3.x.

Do you know how to update to use something else instead of nose?

[felixonmars]

Opened #60 to use pytest instead :)