Add v3.1 to the generation code

[bact]

Once these two issues are resolved,
we can add "3.1" to SPDX_VERSIONS list in generate-bindings code:

1. 3.1 RDF/JSON-LD URL redirections Setup RDF and schema URL redirections for 3.1 spdx-spec#1249
2. 3.1 JSON Schema generation Update publication workflow to use 3.1 context file URL from spdx.org spdx-spec#1358