Bump node-sass from 5.0.0 to 7.0.0 in /ClientApp

Bumps [node-sass](https://github.com/sass/node-sass) from 5.0.0 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](sass/node-sass@v5.0.0...v7.0.0) --- updated-dependencies: - dependency-name: node-sass dependency-type: direct:development ... Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]