Bump _images/icons from 6addf23 to 15aa184 (#3638)

Bumps [_images/icons](https://github.com/elementary/icons) from `6addf23` to `15aa184`.
- [Release notes](https://github.com/elementary/icons/releases)
- [Commits](elementary/icons@6addf23...15aa184)

---
updated-dependencies:
- dependency-name: _images/icons
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>