[FEATURE]: Desktop app ought include the Iosevka font

[ariane-emory]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Iosevka is a beautiful font.

The desktop app ought include it as a font option.

[Spiralyfox]

Iosevka is a great coding font, very readable and modern.
If GitHub Desktop adds more font options, Iosevka would be a strong choice.
A good first step would be letting users pick any installed system font.

[ariane-emory]

@Spiralyfox Any installed font would be even cooler! But that may be more complex to achieve... in the short term, I'd happily settle for Iosevka.