Problem running with mod_wsgi

Hi there, I've been following the installation instructions diligently, but I seem to have run in to a roadblock on first_setup.py:

```
root@numbas:/srv/www/numbas_editor# source bin/activate
(numbas_editor) root@numbas:/srv/www/numbas_editor# python3 first_setup.py
/srv/www/numbas_editor/first_setup.py:11: DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
from pkg_resources import packaging
Traceback (most recent call last):
File "/srv/www/numbas_editor/first_setup.py", line 11, in
from pkg_resources import packaging
ImportError: cannot import name 'packaging' from 'pkg_resources' (/srv/www/numbas_editor/lib/python3.12/site-packages/pkg_resources/__init__.py)
```

Any advice greatly appreciated!

Start with the installation instructions and first_setup.py, especially line 11 where the traceback shows the pkg_resources import failing under Python 3.12. Reproduce the setup error in the reported environment and determine the supported dependency or import path. Done means first_setup.py runs successfully when deployed with mod_wsgi.

Written by the indexing model from the issue text.