chore(deps-dev): update rubocop-rspec requirement from ~> 2.4, >= 2.4.0 to ~> 3.6

Updates the requirements on [rubocop-rspec](https://github.com/rubocop/rubocop-rspec) to permit the latest version.
- [Release notes](https://github.com/rubocop/rubocop-rspec/releases)
- [Changelog](https://github.com/rubocop/rubocop-rspec/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop-rspec@v2.4.0...v3.6.0)

---
updated-dependencies:
- dependency-name: rubocop-rspec
  dependency-version: 3.6.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

Gemfile

@@ -20,6 +20,6 @@ group :plugins do
   gem 'rspec-mocks', '~> 3.10', '>= 3.10.0'
   gem 'rubocop', '~> 1.0'
   gem 'rubocop-rake', '~> 0.6', '>= 0.6.0'
-  gem 'rubocop-rspec', '~> 2.4', '>= 2.4.0'
+  gem 'rubocop-rspec', '~> 3.6'
   gem 'ruby-progressbar', '~> 1.11', '>= 1.11.0'
 end