scripts/sphinx-pre-install: fix Archlinux PDF dependencies

There are some missing packages causing PDF build to fail on
Archlinux and add latexmk (from texlive-binextra package).

Yet, at least today, PDF builds are failing on a very late
stage, when trying to run xdvipdfmx:

$ xdvipdfmx -E -o "peci.pdf" "peci.xdv"
xdvipdfmx:fatal: Unrecognized paper format: # Simply write the paper name. See man 1 paper and "paper --no-size --all" for possible values

Despite its message, even using a very simple document like:

\def\sphinxdocclass{report}
\documentclass[a4paper,11pt,english]{sphinxmanual}
\begin{document}
Test
\end{document}

or even:

\def\sphinxdocclass{report}
\documentclass{sphinxmanual}
\begin{document}
Test
\end{document}

Is causing xdvipdfmx to complain about geometry. As Archlinux is
a rolling release distro, maybe I got it on a bad day. So, let's
fix it in the hope that soon enough someone would fix the issues
there.

Such broken scenario happens with those packages installed:

texlive-basic 2025.2-1
texlive-bin 2025.2-1
texlive-binextra 2025.2-1
texlive-fontsrecommended 2025.2-1
texlive-langchinese 2025.2-1
texlive-langcjk 2025.2-1
texlive-latex 2025.2-1
texlive-latexextra 2025.2-1
texlive-latexrecommended 2025.2-1
texlive-pictures 2025.2-1
texlive-xetex 2025.2-1
python-docutils 1:0.21.2-3
python-sphinx 8.2.3-1
python-sphinx-alabaster-theme 1.0.0-4
python-sphinxcontrib-applehelp 2.0.0-3
python-sphinxcontrib-devhelp 2.0.0-4
python-sphinxcontrib-htmlhelp 2.1.0-3
python-sphinxcontrib-jsmath 1.0.1-19
python-sphinxcontrib-qthelp 2.0.0-3
python-sphinxcontrib-serializinghtml 2.0.0-3

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/574d902f7691861e18339217f42409850ee58791.1755763127.git.mchehab+huawei@kernel.org