build(deps-dev): bump @equinor/fusion-observable from 8.5.5 to 8.5.6 (#2842)

Bumps [@equinor/fusion-observable](https://github.com/equinor/fusion-framework/tree/HEAD/packages/utils/observable) from 8.5.5 to 8.5.6.
- [Release notes](https://github.com/equinor/fusion-framework/releases)
- [Changelog](https://github.com/equinor/fusion-framework/blob/main/packages/utils/observable/CHANGELOG.md)
- [Commits](https://github.com/equinor/fusion-framework/commits/@equinor/fusion-observable@8.5.6/packages/utils/observable)

---
updated-dependencies:
- dependency-name: "@equinor/fusion-observable"
  dependency-version: 8.5.6
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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