OpenAPI 3.0 support

[valerii15298]

Describe the feature

oRPC only supports OpenAPI 3.1.1

But in reality a lot of tools still live in Stone Age and only support OpenAPI 3.0.

Would be nice to have support OpenAPI 3.0.
Here are changes overview from 3.0 to 3.1 from releases: https://github.com/OAI/OpenAPI-Specification/releases
https://github.com/OAI/OpenAPI-Specification/releases/tag/3.1.0-rc0
https://github.com/OAI/OpenAPI-Specification/releases/tag/3.1.0-rc1
https://github.com/OAI/OpenAPI-Specification/releases/tag/3.1.0

Also OpenAPI 3.2 already released(but I expect adoption for it will come not earlier than later in next year) so I would not consider it as a high priority(since most of the tools did not even adopt 3.1)

Additional information

• Would you be willing to help implement this feature?

[dinwwwh]

Maybe down convert solutions can be use as temporary solution: https://github.com/apiture/openapi-down-convert

[dinwwwh]

In next vertion oRPC built-in support 3.0 spec #1998