Is your feature request related to a problem? Please describe.
There are various spinning box ways in the terminal. Fira Code tries to spice that up a bit by providing actual spinning glyphs.

Describe the solution you'd like
I would like gum spin to make use of that and provide support for it via gum spin --spinner=fira with fira denoting that the Fira Code introduce spinning codepoints will be used (see link below).

Describe alternatives you've considered
ASCII arts

Additional context
See https://github.com/tonsky/FiraCode/releases/tag/6 for the release page, description & demo