message: add primer-utilities back to _document.js
diff: @@ -3,17 +3,25 @@ import Document, {Head, Main, NextScript} from 'next/document'
  import {ServerStyleSheet} from 'styled-components'
  import {extractCritical} from 'emotion-server'
  +const customCSS = preval`
  + const {renderSource} = require('../lib/render-sass')
  + module.exports = renderSource('@import "primer-utilities/index.scss";')
  +`
  +
  export default class MyDocument extends Document {
  static getInitialProps({renderPage}) {
  const sheet = new ServerStyleSheet()
  const page = renderPage(App => props => sheet.collectStyles(<App {...props} />))
  - const styles = (
  + return {
  + ...page,
  + styles: (
  <>
  + <style id="primer-custom">{customCSS}</style>
  <style id="emotion-static">{extractCritical(page.html).css}</style>
  {sheet.getStyleElement()}
  </>
  )
  - return {...page, styles}
  + }
  }
  render() {
  