BUG: update pandoc arguments

[pcmoore]

On pandoc v3.1.8, and possibly earlier versions, the following warning is seen when rendering The Notebook. We should verify that the suggested arguments exist on older versions of pandoc and migrate to the new recommended arguments.

[WARNING] Deprecated: --self-contained. use --embed-resources --standalone

[dburgener]

The --embed-resources flag was added in the same commit as the --self-contained flag was deprecated. This was released in pandoc 2.19 on 2022-08-03 https://github.com/jgm/pandoc/blob/main/changelog.md#pandoc-219-2022-08-03

Fedora should have 2.19 or later starting with f39: https://koji.fedoraproject.org/koji/packageinfo?packageID=11560, and f40 is the oldest version still receiving updates.

Ubuntu LTS releases can be pretty ancient: https://en.wikipedia.org/wiki/Ubuntu_version_history. In particular, 20.04 and 22.04 are still in their regular support windows. Ubuntu 20.04 has pandoc 2.5 and 22.04 has pandoc 2.9.2, which are both too old. The latest LTS, 24.04 has 3.1.3, which is new enough: https://launchpad.net/ubuntu/+source/pandoc

I happened to have an Ubuntu 22.04 box up and verified that the warning does not appear there and --embed-resources --standalone is not yet supported.

We're obviously not under an obligation to stay compatible with Ubuntu LTS releases indefinitely, but since the --self-contained version still works on the latest pandoc, my preference would be to leave it as is for backwards compatibility, at least until Ubuntu 20.04 ends its regular support window in May 2025. That would still leave 22.04 as a supported LTS with a version of pandoc that's too old, but waiting until 2027 for it's regular support window to close seems excessive IMO.