Support for OpenAPI 3.2.0

[dineiar]

OpenAPI 3.2.0 was released on Sep 19, despite not being available in the Swagger website yet (as of this writing).

I couldn't find any issue to add support for OpenAPI 3.2.0 in ApiDOM, so I am opening this one.

Thus, this issue is a feature request to add support for OpenAPI 3.2.0 in ApiDOM.