Bump rubocop-rails from 2.14.2 to 2.15.0 (#17922)

Bumps [rubocop-rails](https://github.com/rubocop/rubocop-rails) from 2.14.2 to 2.15.0.
- [Release notes](https://github.com/rubocop/rubocop-rails/releases)
- [Changelog](https://github.com/rubocop/rubocop-rails/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop/rubocop-rails/compare/v2.14.2...v2.15.0)

---
updated-dependencies:
- dependency-name: rubocop-rails
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

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

Gemfile

@@ -146,7 +146,7 @@ group :development, :test do
   gem "rspec-rails", "~> 5.1" # rspec-rails is a testing framework for Rails 3+
   gem "rubocop", "~> 1.30", require: false # Automatic Ruby code style checking tool
   gem "rubocop-performance", "~> 1.14", require: false # A collection of RuboCop cops to check for performance optimizations in Ruby code
-  gem "rubocop-rails", "~> 2.14", require: false # Automatic Rails code style checking tool
+  gem "rubocop-rails", "~> 2.15", require: false # Automatic Rails code style checking tool
   gem "rubocop-rspec", "~> 2.11", require: false # Code style checking for RSpec files
   gem "sassc-rails", "~> 2.1.2" # Integrate SassC-Ruby into Rails
 end

Gemfile.lock

@@ -754,7 +754,7 @@ GEM
     rubocop-performance (1.14.2)
       rubocop (>= 1.7.0, < 2.0)
       rubocop-ast (>= 0.4.0)
-    rubocop-rails (2.14.2)
+    rubocop-rails (2.15.0)
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 1.7.0, < 2.0)
@@ -1068,7 +1068,7 @@ DEPENDENCIES
   rss (~> 0.2.9)
   rubocop (~> 1.30)
   rubocop-performance (~> 1.14)
-  rubocop-rails (~> 2.14)
+  rubocop-rails (~> 2.15)
   rubocop-rspec (~> 2.11)
   ruby-prof (~> 1.4)
   rubyzip (~> 2.3)