Replace gem 'chromedriver-helper' to 'webdrivers' in spec/integration/rails_5.2.5/Gemfile since 'chromedriver-helper' is deprecated

cf. flavorjones/chromedriver-helper#83

Author: nard-tech

spec/integration/rails_5.2.5/Gemfile

@@ -52,7 +52,7 @@ group :test do
   gem 'capybara', '>= 2.15'
   gem 'selenium-webdriver'
   # Easy installation and use of chromedriver to run system tests with Chrome
-  gem 'chromedriver-helper'
+  gem 'webdrivers'
 end
 
 # Windows does not include zoneinfo files, so bundle the tzinfo-data gem