build(deps): bump signature from 2.0.0 to 2.1.0 (#320)

Bumps [signature](https://github.com/RustCrypto/traits) from 2.0.0 to 2.1.0.
- [Release notes](https://github.com/RustCrypto/traits/releases)
- [Commits](https://github.com/RustCrypto/traits/compare/signature/v2.0.0...signature-v2.1.0)

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

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

Cargo.lock

@@ -479,9 +479,9 @@ dependencies = [
 
 [[package]]
 name = "signature"
-version = "2.0.0"
+version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8fe458c98333f9c8152221191a77e2a44e8325d0193484af2e9421a53019e57d"
+checksum = "5e1788eed21689f9cf370582dfc467ef36ed9c707f073528ddafa8d83e3b8500"
 dependencies = [
  "digest",
  "rand_core",