Bump node-sass from 4.12.0 to 7.0.0 in /src

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:development
...

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

src/package.json

@@ -13,7 +13,7 @@
     "css-loader": "^3.2.0",
     "mini-css-extract-plugin": "^0.8.0",
     "optimize-css-assets-webpack-plugin": "^5.0.3",
-    "node-sass": "^4.12.0",
+    "node-sass": "^7.0.0",
     "sass-loader": "^7.2.0",
     "style-loader": "^1.0.0",
     "webpack": "^4.39.2",