Describe the bug

Schema definition in components of combined schemas are failing to be parsed, with the following error:

Unable to parse this part of your OpenAPI document: : Invalid property in union /components/schemas/composite_object

Schema(title=None, multipleOf=None, maximum=None, exclusiveMaximum=None, minimum=None, exclusiveMinimum=None, maxLength=None, minLength=None, pattern=None, maxItems=None, minItems=None, uniqueItems=None, maxProperties=None, minProperties=None, required=None, enum=None, type=None, allOf=[Reference(ref='#/components/schemas/simple_object1'), Reference(ref='#/components/schemas/simple_object2')], oneOf=[], anyOf=[], schema_not=None, items=None, properties=None, additionalProperties=None, description=None, schema_format=None, default=None, nullable=False, discriminator=None, readOnly=None, writeOnly=None, xml=None, externalDocs=None, example=None, deprecated=None)

Surprisingly, combined schemas are correctly parsed when defined in paths : this is the uncommented part in the gist.

OpenAPI Spec File
A link to an OpenAPI document which produces this issue. Ideally, write a minimal reproduction only containing the problematic pieces.

Desktop (please complete the following information):

• OS: Amazon Linux 2
• Python Version: 3.11.5
• openapi-python-client version 0.15.2