fix: module doesn't generate fallback fonts

[avinean]

🐛 The bug

In my case there is a font-family Test.

In build mode nothing changes. No fallback font-face. No fallback in font-family value
In dev mode. No fallback font-face. Fallback in font-family value appears font-family: 'Test', 'Test fallback'

🛠️ To reproduce

https://stackblitz.com/edit/github-hjovjz?file=nuxt.config.ts

🌈 Expected behaviour

@font-face {
  font-family: 'Test';
   ...
}
* {
  font-family: Test;
}

Code above should be transformed to code below


@font-face {
  font-family: 'Test fallback';
  ...
}
*{
  font-family: 'Test', 'Test fallback';
}

ℹ️ Additional context

• Operating System: Darwin
• Node Version: v18.6.0
• Nuxt Version: 3.6.5
• Nitro Version: 2.5.2
• Package Manager: npm@8.13.2
• Builder: vite
• User Config: devtools, modules, css, fontMetrics
• Runtime Modules: @nuxtjs/fontaine@0.4.1
• Build Modules: -