Update rubocop requirement from ~> 1.60.0 to ~> 1.61.0 (#15)

Updates the requirements on [rubocop](https://github.com/rubocop/rubocop) to permit the latest version.
- [Release notes](https://github.com/rubocop/rubocop/releases)
- [Changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v1.60.0...v1.61.0)

---
updated-dependencies:
- dependency-name: rubocop
  dependency-type: direct:production
...

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

Gemfile

@@ -11,6 +11,6 @@ gem 'simplecov', '~> 0.22.0'
 gem 'multipart-parser', '~> 0.1.1'
 gem 'webmock', '~> 3.4'
 
-gem 'rubocop', '~> 1.60.0'
+gem 'rubocop', '~> 1.61.0'
 gem 'rubocop-packaging', '~> 0.5'
 gem 'rubocop-performance', '~> 1.20'