Issue importing mock with sphinx 9.1.0

[dvzrv]

Hi! 👋

On Arch Linux we are trying to use sphinx-argparse in the context of building man pages for khard, but this fails unfortunately: lucc/khard#356

      File "/usr/lib/python3.14/site-packages/sphinxarg/ext.py", line 18, in <module>
        if ismodule(mock):
                    ^^^^
    NameError: name 'mock' is not defined

This seems similar to #82 but fails differently.

Currently, this means we are disabling the man pages for khard, so it would be awesome if this could be resolved (either here or in sphinx).