Bump node-sass from 4.11.0 to 4.12.0

Bumps [node-sass](https://github.com/sass/node-sass) from 4.11.0 to 4.12.0.
- [Release notes](https://github.com/sass/node-sass/releases)
- [Changelog](https://github.com/sass/node-sass/blob/master/CHANGELOG.md)
- [Commits](sass/node-sass@v4.11.0...v4.12.0)

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

package.json

@@ -69,7 +69,7 @@
     "mini-css-extract-plugin": "^0.6.0",
     "modernizr-auto-loader": "^0.1.0",
     "modularscale-sass": "^3.0.3",
-    "node-sass": "^4.11.0",
+    "node-sass": "^4.12.0",
     "optimize-css-assets-webpack-plugin": "^5.0.1",
     "postcss-loader": "^3.0.0",
     "promise-polyfill": "^8.0.0",