### Bug description

I made a mermaid graph where an external image (e.g. https://iconscout.com/ms-icon-310x310.png) is embedded and I am trying to use that entire resulting mermaid graph in a pptx file by processing a qmd file with the option `format: pptx`. However, I fail to render a pptx file that contains the mermaid graph, with an error `ERROR: Internal Error: couldn't determine svg dimensions`, although I successfully render an HTML out of the qmd file in question.


### Steps to reproduce

Please process the following qmd file to render pptx and HTML files: 

````qmd
---
format:
  pptx: default
  html: default
---


<script src="https://unpkg.com/mermaid@8.0.0-rc.8/dist/mermaid.min.js"></script>

## External image on the web

```{mermaid}
graph TD
    A[Christmas] -->|Get money| B(Go shopping)
    B --> C{Let me think}
    C -->|One| D[<img src='https://iconscout.com/ms-icon-310x310.png' width='40' height='40' />]
    C -->|Two| E[iPhone]
    C -->|Three| F[Car]
```

## External image on the local folder

```{mermaid}
graph TD
    A[Christmas] -->|Get money| B(Go shopping)
    B --> C{Let me think}
    C -->|One| D[<img src='./ms-icon-310x310.png' width='40' height='40' />]
    C -->|Two| E[iPhone]
    C -->|Three| F[Car]
```
````


### Expected behavior

The following image made using `mermaid` with an external image should be displayed in a pptx file that Quarto produces:

![image](https://github.com/quarto-dev/quarto-cli/assets/42314553/0cc9e226-c784-404c-aee9-ca8920057f05)

Actually, the 

### Actual behavior

On the command line, the following error and stack trace come up:

```bash
$ quarto preview c:/Users/.../test.qmd --no-browser --no-watch-inputs
ERROR: Internal Error: couldn't determine svg dimensions

This is a bug in quarto. We apologize for the inconvenience.
Please consider reporting it at https://github.com/quarto-dev/quarto-cli. Thank you!

Stack trace:
    at resolveSize (file:///C:/Program%20Files/Quarto/bin/quarto.js:59855:19)
    at eventLoopTick (ext:core/01_core.js:181:11)
    at async makePng (file:///C:/Program%20Files/Quarto/bin/quarto.js:60177:57)
    at async makeDefault (file:///C:/Program%20Files/Quarto/bin/quarto.js:60227:24)
    at async Object.cell (file:///C:/Program%20Files/Quarto/bin/quarto.js:60250:20)
    at async Promise.all (index 0)
    at async Object.document (file:///C:/Program%20Files/Quarto/bin/quarto.js:36179:25)
    at async handleLanguageCells (file:///C:/Program%20Files/Quarto/bin/quarto.js:36150:42)
    at async file:///C:/Program%20Files/Quarto/bin/quarto.js:64332:61
    at async withTimingAsync (file:///C:/Program%20Files/Quarto/bin/quarto.js:19439:25)
```

On the preview pane in VSCode, we can see an incomplete preview, which means that the external image is not shown in the resulting mermaid graph:

![image](https://github.com/quarto-dev/quarto-cli/assets/42314553/3594cc8c-4241-4e2b-871a-cf9e01d4ccd8)


### Your environment

- IDE: VSCode 1.79.0 (user setup)
- OS: Windows 11

### 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 1.33.2: OK
[>] Checking versions of quarto dependencies......OK
[>] Checking Quarto installation......OK
      Version: 1.4.117
      Path: C:\Program Files\Quarto\bin
      CodePage: 932

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

[>] Checking Python 3 installation....OK
      Version: 3.10.11
      Path: C:/Users/<my_username>/AppData/Local/Programs/Python/Python310/python.exe
      Jupyter: 5.3.0
      Kernels: python3

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

[>] Checking R installation...........OK
      Version: 4.3.0
      Path: C:/PROGRA~1/R/R-43~1.0
      LibPaths:
        - C:/Program Files/R/R-4.3.0/library
      knitr: 1.42
      rmarkdown: 2.21

[>] Checking Knitr engine render......OK
```
cscheid
2023-06-14T01:35:26Z
CLRafaelR
enhancement mermaid
Future
open
Fail to render a pptx file that contains a mermaid graph in which an external image is embedded
https://github.com/quarto-dev/quarto-cli/issues/5913