Bump aws-sigv4 from 1.7.0 to 1.8.0

Bumps [aws-sigv4](https://github.com/aws/aws-sdk-ruby) from 1.7.0 to 1.8.0.
- [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@1.7.0...1.8.0)

---
updated-dependencies:
- dependency-name: aws-sigv4
  dependency-type: indirect
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -19,7 +19,7 @@ GEM
       aws-partitions (~> 1, >= 1.651.0)
       aws-sigv4 (~> 1.5)
       jmespath (~> 1, >= 1.6.1)
-    aws-sigv4 (1.7.0)
+    aws-sigv4 (1.8.0)
       aws-eventstream (~> 1, >= 1.0.2)
     byebug (11.1.3)
     codecov (0.6.0)