Bump node-sass in /samples/vuejs-todo-single-file-component

Bumps [node-sass](https://github.com/sass/node-sass) from 4.14.0 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/v4.14.0...v7.0.0)

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

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

samples/vuejs-todo-single-file-component/package.json

@@ -32,7 +32,7 @@
     "ajv": "~5.2.2",
     "css-loader": "^3.5.3",
     "gulp": "~3.9.1",
-    "node-sass": "~4.14.0",
+    "node-sass": "~7.0.0",
     "sass-loader": "~8.0.2",
     "tslint-microsoft-contrib": "5.0.0",
     "vue-loader": "^15.9.1",