Bump node-sass from 4.5.3 to 4.13.1

Bumps [node-sass](https://github.com/sass/node-sass) from 4.5.3 to 4.13.1.
- [Release notes](https://github.com/sass/node-sass/releases)
- [Changelog](https://github.com/sass/node-sass/blob/master/CHANGELOG.md)
- [Commits](sass/node-sass@v4.5.3...v4.13.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package.json

@@ -38,7 +38,7 @@
     "karma-spec-reporter": "0.0.31",
     "karma-webpack": "2.0.4",
     "ngrx-store-freeze": "^0.2.0",
-    "node-sass": "6.0.0",
+    "node-sass": "4.13.1",
     "progress-bar-webpack-plugin": "1.9.3",
     "raw-loader": "0.5.1",
     "rimraf": "2.6.2",