Update chefstyle requirement from = 1.7.2 to = 1.7.4

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@v1.7.2...v1.7.4)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

omnibus.gemspec

@@ -35,7 +35,7 @@ Gem::Specification.new do |gem|
 
   gem.add_development_dependency "artifactory", "~> 3.0"
   gem.add_development_dependency "aruba",       "~> 0.5"
-  gem.add_development_dependency "chefstyle",   "= 1.7.2"
+  gem.add_development_dependency "chefstyle",   "= 1.7.4"
   gem.add_development_dependency "fauxhai-ng",  ">= 7.5"
   gem.add_development_dependency "rspec",       "~> 3.0"
   gem.add_development_dependency "rspec-json_expectations"