Bump the github-actions group with 2 updates (#158)

Bumps the github-actions group with 2 updates: [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) and [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action).


Updates `sigstore/cosign-installer` from 3.8.2 to 3.9.0
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](https://github.com/sigstore/cosign-installer/compare/v3.8.2...v3.9.0)

Updates `docker/setup-buildx-action` from 3.11.0 to 3.11.1
- [Release notes](https://github.com/docker/setup-buildx-action/releases)
- [Commits](https://github.com/docker/setup-buildx-action/compare/v3.11.0...v3.11.1

)

---
updated-dependencies:
- dependency-name: sigstore/cosign-installer
  dependency-version: 3.9.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: github-actions
- dependency-name: docker/setup-buildx-action
  dependency-version: 3.11.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: github-actions
...

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