Fix issue in ArraySchema when items is an Object

[gracekarina]

When this spec is parse, parser doesn't deserialize the items.

openapi: 3.0.0
info:
  version: 0.0.0
  title: test

paths:
  /mixed-array:
    get:
      responses:
        '200':
          description: An array containing strings and/or integers
          content:
            application/json:
              schema:
                type: array
                items:
                  oneOf:
                    - type: string
                    - type: integer