TypeError when model default value is a list

Describe the bug
When generating models for an API where a default argument is a list of enums, a TypeError is raised on this line:

return f"{prop.class_info.name}.{inverse_values[default]}"

A possible fix could be to explicitly check for this case. Below is a proposed fix, but I'm not familiar enough with the codebase to know whether this is a correct fix. However, I was able to parse the API docs correctly with this fix in place:

if type(default) is list:
    return [f"prop.class_info.name.inverse_values[d]" for d in default]
else:
    return f"{prop.class_info.name}.{inverse_values[default]}"

To Reproduce
Steps to reproduce the behavior:

1. Run openapi-python-client generate --url https://sand-docs.ilevelsolutions.eu/openapi.yaml
2. See error

Expected behavior
The API docs should be able to be parsed

OpenAPI Spec File
https://sand-docs.ilevelsolutions.eu/openapi.yaml

Desktop (please complete the following information):

• OS: macOS 13.1
• Python Version: 3.10
• openapi-python-client version: 0.13.1

从 openapi_python_client/parser/properties/init.py 第 463 行附近开始，使用 openapi-python-client generate --url https://sand-docs.ilevelsolutions.eu/openapi.yaml 重现该失败。跟踪列表值 enum 默认值的表示方式，并检查相关的 parser 测试。当 specification 能够成功生成且不出现 TypeError，同时现有行为保持不变时，即视为完成。