### Bug description

If creator provides a valid [author metadata following Author Schema](https://quarto.org/docs/journals/authors.html#author-schema) and convert the `.qmd` file to Markdown, some information in the author metadata is discarted.

### Steps to reproduce

Consider the `index.qmd` file:

```
---
title: "MWE"
author:
  - name:
      given: Jane
      family: Doe
    email: jane@mail.com
    orcid: 0000
    attributes:
      corresponding: true
  - name:
      given: Jonh
      family: Doe
    orcid: 0000
---

Lorem ipsum
```

and run `quarto render index.qmd --to markdown --output rendered_index.md`.

### Expected behavior

Output is identical to the input:

```
---
title: "MWE"
author:
  - name:
      given: Jane
      family: Doe
    email: jane@mail.com
    orcid: 0000
    attributes:
      corresponding: true
  - name:
      given: Jonh
      family: Doe
    orcid: 0000
---

Lorem ipsum
```

This is what happen when using [Hugo format](https://quarto.org/docs/output-formats/hugo.html). `quarto render index.qmd --to hugo-md --output rendered_index.hugo && diff index.qmd rendered_index.hugo` produces

```
17c17
< Lorem ipsum
\ No newline at end of file
---
> Lorem ipsum
```

### Actual behavior

Information in the YAML header is lost:

```
---
author:
- family: Doe
  given: Jane
- family: Doe
  given: Jonh
title: MWE
toc-title: Table of contents
---

Lorem ipsum
```

### Your environment

- OS: Linux 6.2.12-1-MANJARO

### Quarto check output

```
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.2: OK
      Dart Sass version 1.55.0: OK
      Deno version 1.33.2: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.4.176
      Path: /opt/quarto-1.4.176/bin

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.10.10
      Path: /usr/bin/python3
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with python3 -m pip install jupyter

[✓] Checking R installation...........(None)

      Unable to locate an installed version of R.
      Install R from https://cloud.r-project.org/
```
dragonstyle
2023-06-29T15:19:04Z
rgaiacs
bug
v1.4
open
Render Quarto to Markdown remove author information from YAML header
https://github.com/quarto-dev/quarto-cli/issues/6067