Update jsonschema to version 3.0.1 + switch from Draft 4 to Draft 7

[danie1k]

Seems to works flawlessly in my project.

[p1c2u]

@danie1k Why you need Draft7? OpenAPI 3 uses extended subset of JSON Schema Specification Wright Draft 00 (aka Draft5)

The Schema Object allows the definition of input and output data types. These types can be objects, but also primitives and arrays. This object is an extended subset of the JSON Schema Specification Wright Draft 00.

https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#schema-object

[danie1k]

@p1c2u

Why you need Draft7?

The idea started simply - because it's newest available JSON Schema specification version, and draft-05 is officially abandoned.
But it all started from connexion package: zalando/connexion#983 & zalando/connexion#996 which rely on jsonschema (which supports draft-07) + openapi-spec-validator + custom code.

OpenAPI 3 uses extended subset of JSON Schema Specification Wright Draft 00 (aka Draft5)

I haven't know that. It seems that I need to get know better specifications of both, OpenApi & JSON Schema. I've read a lot of documentation, but not much enough; thanks for the link.