Respect main PostCSS sorting config

[AlecRust]

It would be great if this package could respect the main config for postcss-sorting in my package.json e.g.

"postcss": {
  "plugins": {
    "postcss-import": {},
    "postcss-nested": {},
    "postcss-sorting": {
      "properties-order": "alphabetical"
    },
    "autoprefixer": {
      "browsers": "> 5%"
    }
  }
}

Currently I add this underneath as well:

"postcssSortingConfig": {
  "properties-order": "alphabetical"
}