Bump node-sass from 4.13.1 to 7.0.0

Bumps [node-sass](https://github.com/sass/node-sass) from 4.13.1 to 7.0.0.
- [Release notes](https://github.com/sass/node-sass/releases)
- [Changelog](https://github.com/sass/node-sass/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sass/node-sass/compare/v4.13.1...v7.0.0)

---
updated-dependencies:
- dependency-name: node-sass
  dependency-type: direct:development
...

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

package.json

@@ -43,7 +43,7 @@
     "eslint-plugin-jest": "^21.1.0",
     "extract-text-webpack-plugin": "^3.0.0",
     "jest": "^22.0.4",
-    "node-sass": "4.13.1",
+    "node-sass": "7.0.0",
     "npm-run-all": "^4.1.1",
     "postcss-loader": "^2.0.6",
     "pre-commit": "^1.2.2",