packages feed

pandoc-3.14: test/command/8240.md

```
% pandoc -t latex
Header[^fn]:
:    Some other text.

[^fn]: A footnote.
^D
\begin{description}
\tightlist
\item[Header\pandocfootnotemark{1}:]
Some other text.
\end{description}
\pandocfootnotetext{1}{A footnote.}
```