Bump sass-loader from 7.3.1 to 8.0.0

Bumps [sass-loader](https://github.com/webpack-contrib/sass-loader) from 7.3.1 to 8.0.0.
- [Release notes](https://github.com/webpack-contrib/sass-loader/releases)
- [Changelog](https://github.com/webpack-contrib/sass-loader/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/sass-loader/compare/v7.3.1...v8.0.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -36,7 +36,7 @@
     "pug-static-loader": "2.0.0",
     "raven-js": "3.27.2",
     "raw-loader": "3.1.0",
-    "sass-loader": "^7.3.1",
+    "sass-loader": "^8.0.0",
     "shelljs": "0.8.3",
     "source-code-pro": "^2.30.1",
     "source-sans-pro": "2.45.0",