Bump node-sass from 6.0.1 to 7.0.0 in /build

Bumps [node-sass](https://github.com/sass/node-sass) from 6.0.1 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](https://github.com/sass/node-sass/compare/v6.0.1...v7.0.0

)

---
updated-dependencies:
- dependency-name: node-sass
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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