custom code discovery

[d-chambers]

Hi,

I am using pytest-codeblocks to test documentation code snippets that get built with sphinx and the myst_parser. The problem I am running into is that I have to write code blocks like this to get the outuput to show up in documentation:

```{code-cell}
print("mycode")
```

Is there anyway to modify pytest-codeblocks discovery logic to also test these blocks (eg assume "{code-cell}" means "python"

Thanks!