Bump node-sass from 4.14.1 to 7.0.0 in /client

Bumps [node-sass](https://github.com/sass/node-sass) from 4.14.1 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/v4.14.1...v7.0.0)

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

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

client/package.json

@@ -29,7 +29,7 @@
     "connected-react-router": "^6.7.0",
     "eth-sig-util": "^2.5.3",
     "history": "^4.10.1",
-    "node-sass": "^4.14.1",
+    "node-sass": "^7.0.0",
     "react": "^16.13.1",
     "react-dom": "^16.13.1",
     "react-redux": "^7.2.0",