svgelements does not process linear or radial gradient

[tatarize]

https://www.w3.org/TR/SVG/pservers.html#LinearGradientElement

These are URL referenced within the fill element. And link the radialGradient or linearGradient objects defined within the defs of the shadow tree. These would be parsed and linked to fill and stroke attribute of the various defined shapes. This may be a breaking change. As currently those objects would attempt to parse the URI as a string color fail to find it in the lookup table and determine it to default to black.

https://svgwrite.readthedocs.io/en/latest/classes/gradients.html