chore(deps): bump whelk-io/maven-settings-xml-action from 20 to 21

Bumps [whelk-io/maven-settings-xml-action](https://github.com/whelk-io/maven-settings-xml-action) from 20 to 21.
- [Release notes](https://github.com/whelk-io/maven-settings-xml-action/releases)
- [Commits](https://github.com/whelk-io/maven-settings-xml-action/compare/v20...v21

)

---
updated-dependencies:
- dependency-name: whelk-io/maven-settings-xml-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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