Add `vite.config.mjs` to watched paths

[janko]

Description 📖

This ensures building isn't skipped when .mjs extension is used for the Vite config file.

Background 📜

Vite 5 deprecated CJS, so unless "type": "module" is specified in package.json (which requires using .cjs extension things like PostCSS config), the only way to avoid the deprecation warning is to rename the config file to vite.config.mjs.

https://vitejs.dev/guide/migration.html#deprecate-cjs-node-api

The Fix 🔨

I added vite.config.mjs to default watched paths.

[ElMassimo]

Thanks Janko!