Support for schema version draft-07

[andy-maier]

What are you trying to do?

We use schema version draft-07 and get a warning:

UserWarning: Schema version http://json-schema.org/draft-07/schema# not recognized. Some keywords and features may not be supported.

which is understandable since only draft-03 and draft-04 are supported, according to this.

My attempt to fall back to draft-04:

• If we change our $schema attribute to draft-04, we get schema validation errors (jsonschema.exceptions.SchemaError exception from jsonschema.validators.Draft4Validator) for our use of minItems and anyOf.

• The minItems and anyOf keywords are supported in the specification of draft-04.

• Not sure whether this gap in supporting draft-04 is in jsonschema or in python-jsonschema-objects, but it prevents us to fall back to draft-04 at the moment.

Please add support for at least schema version draft-07 (more ideally, also for the final versions 2019-09 and 2020-12.

https://json-schema.org/specification does not even show draft-03 and draft-04 anymore.