Bump prometheus/promci-setup from 0.1.0 to 0.2.1 (#407)

Bumps [prometheus/promci-setup](https://github.com/prometheus/promci-setup) from 0.1.0 to 0.2.1.
- [Release notes](https://github.com/prometheus/promci-setup/releases)
- [Commits](https://github.com/prometheus/promci-setup/compare/5af30ba8c199a91d6c04ebdc3c48e630e355f62d...3e5cd31b34b8ae19efa8f071c5e3cdb44884a7f8)

---
updated-dependencies:
- dependency-name: prometheus/promci-setup
  dependency-version: 0.2.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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