rdf support for 2.3

[armintaenzertng]

The updated 2.3 data model is only supported with the formats tag-value, xml, json and yaml.
The rdf format support for v2.3 has been postponed.

[meretp]

#274 is a subtask of this.

[zvr]

Any estimate for this?

I should note that making a "release" (0.7.0) with a title "Support SPDX 2.3" but not actually supporting one of the official formats is not great publicity for the SPDX project.

[nicoweidner]

The options were to either release with the rdf caveat, or delay the release for an unknown amount of time as rdf is hard to deal with and the existing code is not in great shape. They were discussed in the weekly public meetings, where it was decided that rdf is less important than json/yaml/xml and less important than tag/value, and supporting rdf can be postponed until major refactoring is done. There is no concrete estimate for when it will be implemented.

[armintaenzertng]

Full SPDX 2.3 support is now part of the refactored version found on main.