Bump rubocop from 1.8.1 to 1.9.0

Bumps [rubocop](https://github.com/rubocop-hq/rubocop) from 1.8.1 to 1.9.0.
- [Release notes](https://github.com/rubocop-hq/rubocop/releases)
- [Changelog](https://github.com/rubocop-hq/rubocop/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop-hq/rubocop/compare/v1.8.1...v1.9.0)

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

Gemfile.lock

@@ -71,7 +71,7 @@ GEM
       public_suffix (>= 2.0.2, < 5.0)
     amq-protocol (2.3.2)
     arel (9.0.0)
-    ast (2.4.1)
+    ast (2.4.2)
     autotest (5.0.0)
       minitest-autotest (~> 1.0)
     autotest-rails (4.2.1)
@@ -352,7 +352,7 @@ GEM
       rspec-mocks (~> 3.10)
       rspec-support (~> 3.10)
     rspec-support (3.10.1)
-    rubocop (1.8.1)
+    rubocop (1.9.0)
       parallel (~> 1.10)
       parser (>= 3.0.0.0)
       rainbow (>= 2.2.2, < 4.0)
@@ -361,7 +361,7 @@ GEM
       rubocop-ast (>= 1.2.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.4.0)
+    rubocop-ast (1.4.1)
       parser (>= 2.7.1.5)
     rubocop-rails (2.9.1)
       activesupport (>= 4.2.0)