Bump ionicons from 5.5.4 to 6.0.0 in /searx/static/themes/simple

Bumps [ionicons](https://github.com/ionic-team/ionicons) from 5.5.4 to 6.0.0.
- [Release notes](https://github.com/ionic-team/ionicons/releases)
- [Commits](https://github.com/ionic-team/ionicons/compare/v5.5.4...v6.0.0

)

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

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