Bump grunt-contrib-cssmin in /searx/static/themes/simple

Bumps [grunt-contrib-cssmin](https://github.com/gruntjs/grunt-contrib-cssmin) from 4.0.0 to 5.0.0.
- [Release notes](https://github.com/gruntjs/grunt-contrib-cssmin/releases)
- [Changelog](https://github.com/gruntjs/grunt-contrib-cssmin/blob/main/CHANGELOG)
- [Commits](https://github.com/gruntjs/grunt-contrib-cssmin/compare/v4.0.0...v5.0.0

)

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

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