Bump indexmap from 2.2.3 to 2.2.6

Bumps [indexmap](https://github.com/indexmap-rs/indexmap) from 2.2.3 to 2.2.6.
- [Changelog](https://github.com/indexmap-rs/indexmap/blob/master/RELEASES.md)
- [Commits](indexmap-rs/indexmap@2.2.3...2.2.6)

---
updated-dependencies:
- dependency-name: indexmap
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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