### Bug description

The following mermaid class diagram is rendered wrong, as `<|--` is translated to `&lt;|--`.

Contents of `file.qmd`
````md
---
title: Test
format: gfm
---

```{mermaid}
classDiagram
  Foo <|-- Bar
```
````

Is rendered as `file.md`:

````md
# Test

``` mermaid
classDiagram
  Foo &lt;|-- Bar
```
````

This example uses quarto v1.3.340.

### 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.
- [ ] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [ ] 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.
cscheid
2023-04-26T16:23:16Z
rcannood
bug mermaid
v1.4
open
Rendering issue with mermaid class diagrams in GFM
https://github.com/quarto-dev/quarto-cli/issues/5319