Bump rubocop from 1.8.1 to 1.9.1 (#12506)

Bumps [rubocop](https://github.com/rubocop-hq/rubocop) from 1.8.1 to 1.9.1.
- [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...v1.9.1)

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

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

Gemfile

@@ -147,7 +147,7 @@ group :development, :test do
   gem "knapsack_pro", "~> 2.11.0" # Help parallelize Ruby spec builds
   gem "pry-byebug", "~> 3.8" # Combine 'pry' with 'byebug'. Adds 'step', 'next', 'finish', 'continue' and 'break' commands to control execution
   gem "rspec-rails", "~> 4.0" # rspec-rails is a testing framework for Rails 3+
-  gem "rubocop", "~> 1.8", require: false # Automatic Ruby code style checking tool
+  gem "rubocop", "~> 1.9", require: false # Automatic Ruby code style checking tool
   gem "rubocop-performance", "~> 1.9", require: false # A collection of RuboCop cops to check for performance optimizations in Ruby code
   gem "rubocop-rails", "~> 2.9", require: false # Automatic Rails code style checking tool
   gem "rubocop-rspec", "~> 2.1", require: false # Code style checking for RSpec files

Gemfile.lock

@@ -100,7 +100,7 @@ GEM
     approvals (0.0.24)
       nokogiri (~> 1.6)
       thor (~> 0.18)
-    ast (2.4.1)
+    ast (2.4.2)
     aws-eventstream (1.1.0)
     aws-sigv4 (1.2.2)
       aws-eventstream (~> 1, >= 1.0.2)
@@ -651,7 +651,7 @@ GEM
     rspec-retry (0.6.2)
       rspec-core (> 3.3)
     rspec-support (3.10.1)
-    rubocop (1.8.1)
+    rubocop (1.9.1)
       parallel (~> 1.10)
       parser (>= 3.0.0.0)
       rainbow (>= 2.2.2, < 4.0)
@@ -660,7 +660,7 @@ 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-performance (1.9.2)
       rubocop (>= 0.90.0, < 2.0)
@@ -951,7 +951,7 @@ DEPENDENCIES
   rouge (~> 3.26)
   rspec-rails (~> 4.0)
   rspec-retry (~> 0.6)
-  rubocop (~> 1.8)
+  rubocop (~> 1.9)
   rubocop-performance (~> 1.9)
   rubocop-rails (~> 2.9)
   rubocop-rspec (~> 2.1)