Support for SPDX 2.3?

[nishakm]

Describe the Feature
I'm using tern to generate an SPDX-json formatted SBOM but it only seems to support SDPX 2.2

Use Cases
I would like to generate a SPDX 2.3 document to maintain parity with the SPDX maven plugin

Implementation Changes
Perhaps an SPDX version switch? It may mean a code refactor.

[rnjudge]

@nishakm There's actually a PR ready to merge that covers this using the SPDX python libraries - do you want to take a look? #1233

I meant to review before maternity leave but ran out of time.