build(deps): bump signature from 2.1.0 to 2.2.0 (#990)

Bumps [signature](https://github.com/RustCrypto/traits) from 2.1.0 to 2.2.0.
- [Commits](RustCrypto/traits@signature-v2.1.0...signature-v2.2.0)

---
updated-dependencies:
- dependency-name: signature
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>