Use parcel v2 (parcel@next)

[limonte]

Blocked by parcel-bundler/parcel#5275

Currenty yarn build failing with:

$ parcel build --no-source-maps app.ts
🚨 Build failed.
@parcel/transformer-sass: The @import path "~@sweetalert2/themes/dark/dark.scss" is using webpack specific syntax, which isn't supported by Parcel.

To @import files from node_modules, use "@sweetalert2/themes/dark/dark.scss"
  ╷
7 │ @import '~@sweetalert2/themes/dark/dark.scss';
  │         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  ╵
  styles.scss 7:9  root stylesheet