### Bug description

When I render a qmd file that has inside a [pagebreak](https://quarto.org/docs/authoring/markdown-basics.html#page-breaks), and I render it to docx, I'm not able to open the output and I have this error

![image](https://github.com/quarto-dev/quarto-cli/assets/30607/f3b0d13d-4aaa-49b5-bda4-6902b7b93b5f)


### Steps to reproduce

I have tested using this input and running `quarto render test.qmd --to docx  -o test.docx`.

My OS is Debian 11 and I'm using quarto 1.4.43.


````qmd
---
title: "Title"
format:
  docx:
    toc: false
    number-sections: false
    highlight-style: github
---

# A title

Lorem ipsum

{{< pagebreak >}}

# Another title

Lorem ipsum
````


### Expected behavior

To be able to open a paginated docx.

### Actual behavior

Opening the output in office fow win I have this error

![image](https://github.com/quarto-dev/quarto-cli/assets/30607/5d1e9db2-7851-4278-b42f-d3e7c614e496)


### Your environment

My OS is Debian 11 and I'm using quarto 1.4.43.

### Quarto check output

```bash
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.2: OK
      Dart Sass version 1.55.0: OK
      Deno version 1.33.1: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.4.43
      Path: /opt/quarto/bin

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

[✓] Checking Python 3 installation....OK
      Version: 3.9.2
      Path: /usr/bin/python3
      Jupyter: 5.1.2
      Kernels: bash, python3

[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........OK
      Version: 4.0.4
      Path: /usr/lib/R
      LibPaths:
        - /home/aborruso/R/x86_64-pc-linux-gnu-library/4.0
        - /usr/local/lib/R/site-library
        - /usr/lib/R/site-library
        - /usr/lib/R/library
      knitr: 1.41
      rmarkdown: 2.19

[✓] Checking Knitr engine render......OK
```
cscheid
2023-06-29T13:54:03Z
aborruso
bug docx
closed
pagebreak seems not work for docx
https://github.com/quarto-dev/quarto-cli/issues/6065