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

@@ -4,7 +4,7 @@
   "devDependencies": {
     "@symfony/webpack-encore": "^0.27.0",
     "bootstrap": "^4.4.1",
-    "node-sass": "^4.13.1",
+    "node-sass": "^7.0.0",
     "sass-loader": "^7.3.1",
     "webpack-notifier": "^1.8.0"
   },