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](sass/node-sass@v4.13.1...v7.0.0)

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

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

Author: dependabot[bot]

package.json

@@ -69,7 +69,7 @@
     "html-webpack-plugin": "^3.2.0",
     "lint-staged": "^8.1.5",
     "mocha": "^6.2.2",
-    "node-sass": "^4.12.0",
+    "node-sass": "^7.0.0",
     "sass": "^1.23.0",
     "sass-loader": "^8.0.0",
     "ts-loader": "^6.2.1",