Bump gulp-sass from 5.1.0 to 6.0.0

Bumps [gulp-sass](https://github.com/dlmanning/gulp-sass) from 5.1.0 to 6.0.0.
- [Release notes](https://github.com/dlmanning/gulp-sass/releases)
- [Changelog](https://github.com/dlmanning/gulp-sass/blob/master/CHANGELOG.md)
- [Commits](dlmanning/gulp-sass@v5.1.0...v6.0.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package.json

@@ -29,7 +29,7 @@
     "gulp-jshint": "^2.0.4",
     "gulp-plumber": "^1.1.0",
     "gulp-rename": "^2.0.0",
-    "gulp-sass": "^5.0.0",
+    "gulp-sass": "^6.0.0",
     "gulp-sort": "^2.0.0",
     "gulp-sourcemaps": "^3.0.0",
     "gulp-uglify": "^3.0.2",