Bump node-sass from 4.13.1 to 7.0.0 in /pwa

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:production
...

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

pwa/package.json

@@ -14,7 +14,7 @@
         "@types/react-router-dom": "^5.1.4",
         "antd-mobile": "^2.3.1",
         "easy-peasy": "^3.3.0",
-        "node-sass": "^4.13.1",
+        "node-sass": "^7.0.0",
         "react": "^16.12.0",
         "react-dom": "^16.12.0",
         "react-router-dom": "^5.1.2",