yubioath-flutter doesn't respect font DPI (regression from yubioath-desktop)

[rkjnsn]

I have a higher-density display. 2x UI scaling on this display makes things a little too big for my taste, so instead I've just bumped my font DPI up to 168. This works really well in almost all apps, including the legacy yubioath-desktop. However, yubioath-flutter seems to ignore the font DPI, and as a result renders text as if running on a 96 DPI display, resulting in tiny, uncomfortable-to-read text.

For comparison, here is a screenshot from yubioath-desktop with my DPI setting (scaled here to match the physical size at which it appears on my display):

And here is a screenshot from yubioath-flutter (similarly scaled):