chore(deps-dev): update rubocop requirement from = 1.56.4 to = 1.57.0 (#503)

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@v1.56.4...v1.57.0)

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

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

Author: dependabot[bot]

appium_lib_core.gemspec

@@ -30,7 +30,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'minitest', '~> 5.0'
   spec.add_development_dependency 'minitest-reporters', '~> 1.1'
   spec.add_development_dependency 'webmock', '~> 3.19.0'
-  spec.add_development_dependency 'rubocop', '1.56.4'
+  spec.add_development_dependency 'rubocop', '1.57.0'
   spec.add_development_dependency 'appium_thor', '~> 1.0'
   spec.add_development_dependency 'parallel_tests'
   spec.add_development_dependency 'simplecov'