Bump grunt-sass from 3.1.0 to 4.0.0

Bumps [grunt-sass](https://github.com/sindresorhus/grunt-sass) from 3.1.0 to 4.0.0.
- [Release notes](https://github.com/sindresorhus/grunt-sass/releases)
- [Commits](sindresorhus/grunt-sass@v3.1.0...v4.0.0)

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

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

Author: dependabot[bot]

package.json

@@ -21,7 +21,7 @@
     "grunt-contrib-jshint": "3.2.0",
     "grunt-contrib-watch": "1.1.0",
     "grunt-replace-regex": "1.0.3",
-    "grunt-sass": "3.1.0",
+    "grunt-sass": "4.0.0",
     "grunt-stylelint": "0.20.1",
     "grunt-terser": "2.0.0",
     "load-grunt-tasks": "5.1.0",