Add support for OpenAPI v4 Moonwalk

[immanuelfodor]

I didn't see any issue tracking the upcoming OpenAPI v4 spec support, so I thought I would open one.
It's planned to be released by the end of 2024.

OpenAPI v4 Moonwalk SIG repo: https://github.com/OAI/sig-moonwalk

Announcement: https://www.openapis.org/blog/2023/12/06/openapi-moonwalk-2024

[daveshanley]

Yep, 100%.

As soon as the standard is settled, it will be included in the library and new models etc will be available for v4

[LasneF]

@immanuelfodor , @daveshanley , you can be calm on this one, moonwalk will not be released this year for 100 % sure ,
the OAS target is to realease 3.1.1 and 3.0.4 asap ,with no change just precision, and focus on 3.2.0
Moonwalk is still exploratory and may not be there soon