Bump node-sass from 4.12.0 to 7.0.0

Bumps [node-sass](https://github.com/sass/node-sass) from 4.12.0 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/v4.12.0...v7.0.0)

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

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

package.json

@@ -10,7 +10,7 @@
     "@types/react-router-dom": "^4.3.4",
     "classnames": "^2.2.6",
     "immutable": "^4.0.0-rc.12",
-    "node-sass": "^4.12.0",
+    "node-sass": "^7.0.0",
     "react": "^16.8.6",
     "react-dom": "^16.8.6",
     "react-loadable": "^5.5.0",