### Bug description

A fontawesome shortcode no longer works in a subtitle in pre-release v1.4.63 (works in the current release):

```
---
title: "test"
subtitle: "With this icon {{< fa regular heart >}}"
---

This is a Quarto website. {{< fa regular heart >}}

To learn more about Quarto websites visit <https://quarto.org/docs/websites>.

```{r}
1 + 1
```
```
<img width="755" alt="Screenshot 2023-05-16 at 12 42 40" src="https://github.com/quarto-dev/quarto-cli/assets/32419319/0e98d93c-e21f-4942-9802-a3785b7f50de">

[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.2: OK
      Dart Sass version 1.55.0: OK
      NOTE: Deno version 1.33.2 is too old. Please upgrade to 1.33.1 or later.
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.4.63
      Path: /Applications/quarto/bin

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

[✓] Checking Python 3 installation....OK
      Version: 3.9.6
      Path: /Library/Developer/CommandLineTools/usr/bin/python3
      Jupyter: (None)

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

[✓] Checking R installation...........OK
      Version: 4.3.0
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Library/Frameworks/R.framework/Versions/4.3-arm64/Resources/library
      knitr: 1.42
      rmarkdown: 2.21

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

RStudio Version 2023.03.1+446 (2023.03.1+446)

MacOS Ventura 13.3.1



### Checklist

- [X] Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
- [X] Please [format your issue](https://quarto.org/bug-reports.html#formatting-make-githubs-markdown-work-for-us) so it is easier for us to read the bug report.
- [X] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [X] Please document the operating system you're running. If on Linux, please provide the specific distribution.
- [X] Please provide the output of `quarto check` so we know which version of quarto and its dependencies you're running.
2023-05-16T11:51:45Z
cgoo4
duplicate
closed
Fontawesome shortcode in a `.qmd` subtitle
https://github.com/quarto-dev/quarto-cli/issues/5561