Update jwt dependency version to ~> 3.0

Author: uxxman

intercom-rails.gemspec

@@ -19,7 +19,7 @@ Gem::Specification.new do |s|
   s.test_files = Dir["test/**/*"]
 
   s.add_dependency 'activesupport', '>4.0'
-  s.add_dependency 'jwt', '~> 2.0'
+  s.add_dependency 'jwt', '~> 3.0'
 
   s.add_development_dependency 'rake'
   s.add_development_dependency 'actionpack', '>5.0'