feat(example): monospace text style in _CodeDialog

[TENX-S]

Use monospaced style in _CodeDialog to improve readability.

[Jupi007]

Great 👍
But maybe should we import the ubuntu mono font into this project directly.
Byw this could be helpful for the datetime picker.
Wdyt @Feichtmeier ?

[TENX-S]

Please take another look

[Feichtmeier]

I think the font adding in the yaru pubspec is enough, the example should then use the font by using the yaru package from path

[Jupi007]

Yes I think you're right @Feichtmeier