fix(manuscript): update header to include keepaspectratio in includegraphics

```latex
\def\maxwidth{\ifdim\Gin@nat@width>\linewidth\linewidth\else\Gin@nat@width\fi}
\def\maxheight{\ifdim\Gin@nat@height>\textheight\textheight\else\Gin@nat@height\fi}
\makeatother
% Scale images if necessary, so that they will not overflow the page
% margins by default, and it is still possible to overwrite the defaults
% using explicit options in \includegraphics[width, height, ...]{}
\setkeys{Gin}{width=\maxwidth,height=\maxheight,keepaspectratio}
```

was changed to

```latex
\newsavebox\pandoc@box
\newcommand*\pandocbounded[1]{% scales image to fit in text height/width
  \sbox\pandoc@box{#1}%
  \Gscale@div\@tempa{\textheight}{\dimexpr\ht\pandoc@box+\dp\pandoc@box\relax}%
  \Gscale@div\@tempb{\linewidth}{\wd\pandoc@box}%
  \ifdim\@tempb\p@<\@tempa\p@\let\@tempa\@tempb\fi% select the smaller of both
  \ifdim\@tempa\p@<\p@\scalebox{\@tempa}{\usebox\pandoc@box}%
  \else\usebox{\pandoc@box}%
  \fi%
}
```

which is probably related to using a pandoc version that is incompatible with the given quarto version
e.g. 1.6.42 with pandoc 3.1.1

Signed-off-by: Cameron Smith <cameron.ray.smith@gmail.com>

Author: cameronraysmith

reproducibility/manuscript/header.tex

@@ -6,3 +6,6 @@
 % \usepackage{showframe}
 % \usepackage{layout}
 \allowdisplaybreaks
+
+\let\oldincludegraphics\includegraphics
+\renewcommand{\includegraphics}[2][]{\oldincludegraphics[#1,keepaspectratio]{#2}}