this.curl发起请求，无法带上自定义header
### Your detail info about the Bug:


如下是一个调用OpenAI api的controller，请求OpenAI API接口的时候，自定义header带不上。
const Controller = require('egg').Controller;

class OpenAIController extends Controller {
  async completions() {
    const param = this.ctx.request.body;
    const apiUrl = `${this.config.openai.baseUrl}/completions`;
    try {
      const result = await this.ctx.curl(apiUrl, {
        method: 'POST',
        contentType: 'json',
        headers: {
          Authorization: `Bearer ${this.config.openai.apiKey}}`,
        },
        data: param,
        streaming: param.stream,
        dataType: 'json',
      });
      this.ctx.status = result.status;
      this.ctx.set(result.header);
      this.ctx.body = result.data;
    } catch (error) {
      this.ctx.status = 200;
      this.ctx.body = { error: 'error' };
      this.ctx.logger.info('OpenAI API call failed:', error);
    }
  }
}

module.exports = OpenAIController;

如下是抓包的结果：
<img width="394" alt="image" src="https://github.com/eggjs/egg/assets/1320387/a7ddd3e5-534b-4a2d-9fa0-1b7846d46b65">
从抓包的请求中可以看到，并没有自定义headers Authorization 这个请求头，这个是不符合预期的。


### Reproduction Repo

[归档.zip](https://github.com/eggjs/egg/files/12138656/default.zip)


### Node Version

V16.20.1

### Eggjs Version

3

### Plugin Name and its version

无

### Platform and its version

mac