Bump rubocop from 1.19.1 to 1.20.0 (#16674)

Bumps [rubocop](https://github.com/rubocop/rubocop) from 1.19.1 to 1.20.0.
- [Release notes](https://github.com/rubocop/rubocop/releases)
- [Changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop/rubocop/compare/v1.19.1...v1.20.0)

---
updated-dependencies:
- dependency-name: rubocop
  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

@@ -134,7 +134,7 @@ group :development do
   gem 'letter_opener', '~> 1.7'
   gem 'letter_opener_web', '~> 1.4'
   gem 'memory_profiler'
-  gem 'rubocop', '~> 1.19', require: false
+  gem 'rubocop', '~> 1.20', require: false
   gem 'rubocop-rails', '~> 2.11', require: false
   gem 'brakeman', '~> 5.1', require: false
   gem 'bundler-audit', '~> 0.8', require: false