[feature]: OpenAPI 3.1 import: Support DELETE with request body

[xiic]

Is there an existing issue for this?

• I have searched the existing issues

Summary

Add support for OpenAPI 3.1

Why should this be worked on?

Starting with OpenAPI 3.1, it is allowed, although discouraged, to have a request body for GET/HEAD/DELETE requests (see OAI/OpenAPI-Specification#2117). Maybe there are other things regarding OpenAPI 3.1 as well.

Currently it complains that the definition is invalid. This is an (valid) example for an OpenAPI 3.1.0 spec:

openapi: 3.1.0
info:
  title: Testapi
  version: 1.0.0
paths:
  /api/dummy:
    delete:
      description: delete with body
      responses:
        '204':
          description: Success, No content
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/mydto'
components:
  schemas:
    mydto:
      description: testobject
      required:
        - test
      type: object
      properties:
        test:
          type: string