Add support for Python 3.12

[rgaudin]

We are using pkg_resources which have been removed

[benoit74]

Could you (again, sorry) point me to where it is used in scraperlib?

[rgaudin]

I can't find it!

[benoit74]

CI found it for us: https://github.com/openzim/python-scraperlib/actions/runs/7802293999/job/21279404181?pr=127 🤣

The problem is in the i639 package in fact.

[benoit74]

Sorry, "iso-639"

[benoit74]

FYI, I'm trying a move to https://pypi.org/project/iso639-lang/ which seems maintained and supporting everything we need.

[rgaudin]

OK; I remember that was a petty reason to use it but I suppose if tests pass it's OK