Fixed ppi of settingswithspinner image

My previous addition of a settingswithspinner image breaks the pdf documentation, with the weird error

    pdfTeX warning: pdflatex: arithmetic: number too big
    <settingswithspinner_kivy.jpg, id=7002, --32768.0pt x 0.0pt>

I don't really know the details, but I did find that my screenshot had ppi=1x1 in the metadata, so it reported a ridiculous physical size that maybe LaTeX didn't like. This commit fixes that issue to give the same ppi and physical size as the old image, so it hopefully lets the docs build.