Meta: add issues for supporting newest draft

[dragonwasrobot]

Newest JSON schema specs are:

• Core: https://json-schema.org/draft/2020-12/json-schema-core.html
• Validation: https://json-schema.org/draft/2020-12/json-schema-validation.html

First go through:

• https://json-schema.org/draft-06/json-schema-release-notes.html
• https://json-schema.org/draft-07/json-schema-release-notes.html
• https://json-schema.org/draft/2019-09/release-notes.html
• https://json-schema.org/draft/2020-12/release-notes.html
  to know what needs to be changed.