Update chefstyle requirement from = 1.1.3 to = 1.2.0

Updates the requirements on [chefstyle](https://github.com/chef/chefstyle) to permit the latest version.
- [Release notes](https://github.com/chef/chefstyle/releases)
- [Changelog](https://github.com/chef/chefstyle/blob/master/CHANGELOG.md)
- [Commits](chef/chefstyle@v1.1.3...v1.2.0)

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

omnibus.gemspec

@@ -36,7 +36,7 @@ Gem::Specification.new do |gem|
 
   gem.add_development_dependency "artifactory", "~> 3.0"
   gem.add_development_dependency "aruba",       "~> 0.5"
-  gem.add_development_dependency "chefstyle",   "= 1.1.3"
+  gem.add_development_dependency "chefstyle",   "= 1.2.0"
   gem.add_development_dependency "fauxhai",     ">= 5.2"
   gem.add_development_dependency "rspec",       "~> 3.0"
   gem.add_development_dependency "rspec-json_expectations"