uri-reference format not supported in draft-04

[ghost]

The schema says that certain properties have "format": "uri-reference". But we declare our schema as conforming to draft-04, and uri-reference was not introduced until draft-05 (never released) and officially in draft-06.

We should redeclare the schema as draft-07 (actually https://json-schema.org/specification.html says that "draft-handrews-json-schema-01" is the new versioning hotness). According to https://json-schema.org/draft-06/json-schema-release-notes.html, the only back-compat issue that affects us is the change from id to $id.

This is also filed in oasis-tcs/sarif-spec#421.

[ghost]

Fixed in #1523.