inkscape_tools: fix Inkscape version detection on Ubuntu
inkscape_tools: fix Inkscape version detection on Ubuntu

The regex detecting the Inkscape version was too permissive and expected
3 numbers. This make it wrongly match to the revision string on Ubuntu
where the version string has 2 numbers:

Inkscape 0.91 r13725

Reported-by: Romain Chanoir <329309c4c29ba1728fdd0d36d24025b480503bab@viacesi.fr>
Signed-off-by: Alexis Laferrière <b039e421609d7f6745b4f3c2461976cf9144304c@xymus.net>

privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit