fix: boolean for SchemaObject#additionalProperties
fix: boolean for SchemaObject#additionalProperties

Fix the type definition of SchmaObject to follow the spec
https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.1.md#schema-object

> additionalProperties
> Value can be boolean or object. Inline or referenced schema MUST be
> of a Schema Object and not a standard JSON Schema.

metadevpro/openapi3-ts