build(deps): bump github.com/sigstore/cosign/v2 in /hack/tools

Bumps [github.com/sigstore/cosign/v2](https://github.com/sigstore/cosign) from 2.0.3-0.20230614173616-4a2f67e796b9 to 2.2.1.
- [Release notes](https://github.com/sigstore/cosign/releases)
- [Changelog](https://github.com/sigstore/cosign/blob/main/CHANGELOG.md)
- [Commits](https://github.com/sigstore/cosign/commits/v2.2.1)

---
updated-dependencies:
- dependency-name: github.com/sigstore/cosign/v2
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>