Fix builds by swapping to webdrivers instead of locking selenium-webdriver (#2112)

Author: twalpole

example_app_generator/generate_app.rb

@@ -33,7 +33,7 @@
   end
 
   if Rails::VERSION::STRING >= "5.1.0"
-    gsub_file "Gemfile", /.*selenium-webdriver.*/, "gem 'selenium-webdriver', '<= 3.14'"
+    gsub_file "Gemfile", /.*chromedriver-helper.*/, "gem 'webdrivers'"
   end
 
   if Rails::VERSION::STRING >= '5.2.0' && Rails::VERSION::STRING < '6'