[BUG] Smart quotes do not work in export when language is en-gb

[ch . emacs]

Hello,

When exporting a document to LaTeX with smart quotes enabled, I found 
that this had been ignored (e.g. "hello" vs ``hello'' in the output). I 
had the document language set to en-gb, which it seems disables smart 
quotes, as there is no corresponding entry in org-export-smart-quotes 
alist. This is inconsistent with org-latex-language-alist, which 
correctly handles the en-gb case for babel and polyglossia.

I did find some old discussion on the ML about how the algorithm may 
have to be adjusted to accommodate “British style” quoting (single outer 
and double inner quotes) but failing a consensus on that (I am British 
but personally do not use that style), I think it at least makes sense 
to replicate the en(-us) behaviour.

As far as I can tell, this applies to en-au and en-nz too.

Corin Hoad

Emacs  : GNU Emacs 28.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 
3.24.36, cairo version 1.16.0)
Package: Org mode version 9.6 (9.6-??-bed47b4 @ 
/home/corin/.emacs.d/.local/straight/build-28.2/org/)