Short captions for figures for pandoc 3.0+

[prakaa]

If anyone else is like me and is trying to use short-captions with pandoc 3.0+, you'll notice it doesn't work because pandoc Lua has been updated to use Figures.

jpcirrus has written a very simple and concise fix here: jgm/pandoc#7915 (comment)

table-short-captions still works.

Note that this may be addressed within pandoc itself, there is an open PR that may resolve this: jgm/pandoc#8617