[Markdown] Codeblock syntax not applied correctly.

[Sollace]

Describe the bug

Cinny supports markdown's codeblocks with the triple backtick (```) but fails to parse it when the content is all placed on one line.

For example, I expect both codeblocks in this segment to render the same output.

````codeblock```

```
codeblock
```

Instead cinny produces an output like this:

` codeblock`

codeblock

Reproduction

No response

Expected behavior

No response

Platform and versions

Cinny v4.10.0 (flatpak)

Additional context