Complete JSON Schema 1.0 for VERS tests

[mjherzog]

This issue is for tracking the completion of the JSON Schema for VERS tests. The current draft has been set as v0.1 and is available at:

• schemas/vers-test.schema-0.1.json
• https://packageurl.org/schemas/vers-test.schema-0.1.json

Completing this schema is dependent on #46

[tschmidtb51]

Could you please use JSON Draft 2020-12 instead of Draft-07?

[mjherzog]

@tschmidtb51 We had a pretty thorough discussion of using JSON Schema Draft 2020-12 vs Draft-07 for PURL and the conclusion was that there was nothing we needed from 2020-12 that was not already in Draft-07. It is too late to change for PURL because we have completed the Ecma submission for the first edition, but we could possibly change the version for VERS. It would be helpful to know what Draft 2020-12 features you think are important for VERS.