Bump aws-sigv4 from 1.5.2 to 1.6.0 (#841)

Bumps [aws-sigv4](https://github.com/aws/aws-sdk-ruby) from 1.5.2 to 1.6.0.
- [Release notes](https://github.com/aws/aws-sdk-ruby/releases)
- [Changelog](https://github.com/aws/aws-sdk-ruby/blob/version-3/gems/aws-sigv4/CHANGELOG.md)
- [Commits](aws/aws-sdk-ruby@1.5.2...1.6.0)

---
updated-dependencies:
- dependency-name: aws-sigv4
  dependency-type: indirect
  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>

gems.locked

@@ -16,7 +16,7 @@ GEM
       aws-sdk-core (~> 3, >= 3.174.0)
       aws-sdk-kms (~> 1)
       aws-sigv4 (~> 1.4)
-    aws-sigv4 (1.5.2)
+    aws-sigv4 (1.6.0)
       aws-eventstream (~> 1, >= 1.0.2)
     childprocess (4.1.0)
     concurrent-ruby (1.2.2)