Bump rubocop from 1.6.0 to 1.6.1

Bumps [rubocop](https://github.com/rubocop-hq/rubocop) from 1.6.0 to 1.6.1.
- [Release notes](https://github.com/rubocop-hq/rubocop/releases)
- [Changelog](https://github.com/rubocop-hq/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v1.6.0...v1.6.1)

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

Gemfile.lock

@@ -184,7 +184,7 @@ GEM
       rspec-mocks (~> 3.8.0)
       rspec-support (~> 3.8.0)
     rspec-support (3.8.3)
-    rubocop (1.6.0)
+    rubocop (1.6.1)
       parallel (~> 1.10)
       parser (>= 2.7.1.5)
       rainbow (>= 2.2.2, < 4.0)