Build(deps-dev): Bump find-unused-sass-variables from 5.0.0 to 6.0.0 (#39858)

Build(deps-dev): Bump find-unused-sass-variables from 5.0.0 to 6.0.0 (#39858)

Bumps [find-unused-sass-variables](https://github.com/XhmikosR/find-unused-sass-variables) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/XhmikosR/find-unused-sass-variables/releases)
- [Commits](https://github.com/XhmikosR/find-unused-sass-variables/compare/v5.0.0...v6.0.0)

---
updated-dependencies:
- dependency-name: find-unused-sass-variables
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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