Update rubocop requirement from ~> 1.47.0 to ~> 1.48.1

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@v1.47.0...v1.48.1)

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

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

colorls.gemspec

@@ -75,7 +75,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'ronn', '~> 0'
   spec.add_development_dependency 'rspec', '~> 3.7'
   spec.add_development_dependency 'rspec-its', '~> 1.2'
-  spec.add_development_dependency 'rubocop', '~> 1.47.0'
+  spec.add_development_dependency 'rubocop', '~> 1.48.1'
   spec.add_development_dependency 'rubocop-performance', '~> 1.16.0'
   spec.add_development_dependency 'rubocop-rake', '~> 0.5'
   spec.add_development_dependency 'rubocop-rspec', '~> 2.18.1'