Inkscape export errors

[Ekaitz Zarraga <ekaitz@elenq.tech>]

Hi,

I'm experiencing export errors in Inkscape 1.0.1 on several formats like DXF or Optimized SVG. I'm getting the following error:

```
Traceback (most recent call last):
  File "output_scour.py", line 8, in <module>
    import inkex
  File "/gnu/store/ky8vkkxi4b7a3bqlbmlagmv5j2vdnafb-inkscape-1.0.1/share/inkscape/extensions/inkex/__init__.py", line 11, in <module>
    from .extensions import *
  File "/gnu/store/ky8vkkxi4b7a3bqlbmlagmv5j2vdnafb-inkscape-1.0.1/share/inkscape/extensions/inkex/extensions.py", line 33, in <module>
    from .elements import load_svg, BaseElement, ShapeElement, Group, Layer, Grid, \
  File "/gnu/store/ky8vkkxi4b7a3bqlbmlagmv5j2vdnafb-inkscape-1.0.1/share/inkscape/extensions/inkex/elements/__init__.py", line 8, in <module>
    from ._base import SVG_PARSER, load_svg, ShapeElement, BaseElement
  File "/gnu/store/ky8vkkxi4b7a3bqlbmlagmv5j2vdnafb-inkscape-1.0.1/share/inkscape/extensions/inkex/elements/_base.py", line 31, in <module>
    from lxml import etree
ModuleNotFoundError: No module named 'lxml'
```

I suppose it's because python-lxml package is not included in Inkscape. Is there any reason for that?

I tried to edit package description to add python-lxml as a propagated input but it didn't work. Why is that?
Also, adding python-lxml as a propagated input should leave it available system wide, shouldn't it? Am I getting this wrong?

Thanks for your help.

Cheers,
Ekaitz