Bump gulp-sass from 4.1.0 to 5.1.0

Bumps [gulp-sass](https://github.com/dlmanning/gulp-sass) from 4.1.0 to 5.1.0.
- [Release notes](https://github.com/dlmanning/gulp-sass/releases)
- [Changelog](https://github.com/dlmanning/gulp-sass/blob/master/CHANGELOG.md)
- [Commits](dlmanning/gulp-sass@v4.1.0...v5.1.0)

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

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

Author: dependabot[bot]