Update rails dependency in gemspec

Author: Nina Kaufman

chatops-controller.gemspec

@@ -17,7 +17,7 @@ Gem::Specification.new do |s|
   s.files = Dir["{app,config,db,lib}/**/*", "README.md"]
   s.test_files = Dir["spec/**/*"]
 
-  s.add_dependency "rails", ">= 4.0"
+  s.add_dependency "rails", ">= 6.0"
 
   s.add_development_dependency "rspec-rails", "~> 3"
   s.add_development_dependency "pry", "~> 0"