FiraCode Nerd Font not considered as a monospace font
#### 🗹 Requirements

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#### 🎯 Subject of the issue

Experienced behavior:
`FiraCode Nerd Font` is not considered a monospace font by the OS, meanwhile, `FiraCode Nerd Font Mono` is correctly recognized as a monospace font.

I created a smart collection in Font Book, which filters by `Design style is monospace`. `FiraCode Nerd Font` is NOT in the collection, while `FiraCode Nerd Font Mono` does.

Expected behavior:
`FiraCode Nerd Font` is recognized as a monospace font.

Example symbols:
Not applicable.

#### 🔧 Your Setup

- _Which font are you using (e.g. `Anonymice Powerline Nerd Font Complete.ttf`)?_
   - [Release v2.2.2](https://github.com/ryanoasis/nerd-fonts/releases/tag/v2.2.2) of [`Fira Code Retina Nerd Font Complete.ttf`, `Fira Code Bold Nerd Font Complete.ttf`, etc.](https://github.com/ryanoasis/nerd-fonts/releases/download/v2.2.2/FiraCode.zip)
   - The whole family is affected.
- _Which terminal emulator are you using (e.g. `iterm2`, `urxvt`, `gnome`, `konsole`)?_
   - `kitty`
   - I can force it to use `FiraCode Nerd Font` without problem though, but some applications prompt warnings regarding the font.
- _Are you using OS X, Linux or Windows? And which specific version or distribution?_
   - MacOS Catalina 10.15.7

#### ★ Screenshots (Optional)

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