Update dependency node-sass to v7 [SECURITY]

Author: renovate[bot]

src/frontend/package.json

@@ -123,7 +123,7 @@
         "html-loader": "0.5.5",
         "html-webpack-plugin": "3.2.0",
         "lint-staged": "9.5.0",
-        "node-sass": "4.13.0",
+        "node-sass": "7.0.0",
         "prettier": "1.19.1",
         "pretty-quick": "1.11.1",
         "react-hot-loader": "4.12.18",