Support new `upload` field type

GitHub now have this new type:
https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/syntax-for-githubs-form-schema#upload

Using the parser I see this error:
```
Error: Unknown field type: upload
```

It would be good to provide support. Or at least omit it so it doesn't break.

从输出“Unknown field type: upload”的parser入口开始，将其支持的字段类型与GitHub的upload schema文档进行比较。定义解析或省略upload字段时的预期行为，然后验证现有字段的解析仍然有效，并且upload不再中断处理。

由索引模型根据 Issue 内容生成。