Hi!

While rebuilding the python related packages against the Python 3.15rc2
version we found that sphinx-toolbox fails to build from source [1].

It fails with the following error: ModuleNotFoundError: No module named
'sre_parse'. Did you mean: 'argparse'?

This is because sre_parse was deprecated in python 3.11, and removed in
python 3.15.

I've added a patch that uses re._parser and re._constants instead. And
applied the fix in the sandbox [2], to be able to build the packages
that depend on sphinx-toolbox, please consider applying the patch to
support the upcoming 3.15 version.

Setting the severity to important for now. Once Python 3.15 is released,
it will be added to python3-defaults and this bug will become release
critical.

Happy hacking,

[1]: https://debusine.debian.net/debian/r-python-python3.15/artifact/4545233/
[2]: https://debusine.debian.net/debian/r-python-python3.15/