Fix CairoMakie behavior for figure width and dpi settings

[jkrumbiegel]

Copying a message from Slack:

the way it works in Makie 0.20 is that we mostly treat the unit in px_per_unit as the CSS px, or device independent pixel. The px in px_per_unit is then the real image pixel. When a quarto document requests some dpi which means dots per inch, or effectively pixels per inch these days, then the pixels in that is referring to real image pixels. And inch is obviously a real-world metric that doesn't change, but so is the CSS pixel, which has a fixed conversion to inches.
So, we want to convert the fig_width and fig_height which are given in inches to CSS pixels. This is done by multiplying with 96. Then these numbers should be the Makie figure size. The px_per_unit value we need to set to achieve the given dpi we can calculate similarly. 300 dots per inch == 300 / 96 dots per CSS pixel == 3.125 px_per_unit

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e950ac2) 84.48% compared to head (83bdde2) 84.21%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #14      +/-   ##
==========================================
- Coverage   84.48%   84.21%   -0.28%     
==========================================
  Files           5        5              
  Lines         361      361              
==========================================
- Hits          305      304       -1     
- Misses         56       57       +1     

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[jkrumbiegel]

Not sure what the failures on Windows 1.6 are about

[MichaelHatherly]

Not sure what the failures on Windows 1.6 are about

Seen it before sometimes, intermittent issue, rerunning the failed job usually helps.

[jkrumbiegel]

Ok it went through, codecov is just one line that I don't know about. If you're ok with that you can merge.

[MichaelHatherly]

Thanks 😄