[Security] Bump node-sass from 4.11.0 to 4.13.1

Bumps [node-sass](https://github.com/sass/node-sass) from 4.11.0 to 4.13.1. **This update includes a security fix.**
- [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...v4.13.1)

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

package.json

@@ -43,7 +43,7 @@
     "lodash": "^4.17.15",
     "mini-css-extract-plugin": "^0.5.0",
     "mocha": "^6.0.0",
-    "node-sass": "^4.11.0",
+    "node-sass": "^4.13.1",
     "nyc": "^13.1.0",
     "optimize-css-assets-webpack-plugin": "^5.0.1",
     "require-hooks": "0.0.6",