Syntax for multi-line figure captions in Python code cells

[astoeriko]

Some of my figure captions are quite long, so I would like to split them into several lines in the source code for better readability. What is the right syntax for this? Based on the instructions for mermaid diagrams that I found here I tried as follows:

```{python}
#| fig-cap: |
#|   This is a caption for my figure.
#|   It is long, so I put it onto two lines
import numpy as np
import matplotlib.pyplot as plt
plt.plot(np.arange(10))
```

But when I run quarto render, I get an error:

Executing 'test.ipynb'
  Cell 1/1...ERROR: 

None of the known patterns match for   It is long, so I put it onto two lines

It runs fine if I put all the caption onto one line, but this is impractical with caption that are several sentences long.

```{python}
#| fig-cap: "This is a caption for my figure. It is long, so I put it onto two lines."
import numpy as np
import matplotlib.pyplot as plt
plt.plot(np.arange(10))
```

[cderv]

It seems like an issue with our parser so I'll move this to an issue #5413