Remove upper dependency version limit on activesupport

With the release of Rails 8.0.0.1 the dependency update I made as
part of #402 is too strict
and the gem gets downgraded to version 0.23.1.

It might be better to remove the upper ceiling on `activesupport`
so this doesn't become a recurring blocker for future rails
releases

Author: drobny

hutch.gemspec

@@ -10,7 +10,7 @@ Gem::Specification.new do |gem|
   end
   gem.add_runtime_dependency 'carrot-top', '~> 0.0.7'
   gem.add_runtime_dependency 'multi_json', '~> 1.15'
-  gem.add_runtime_dependency 'activesupport', '>= 4.2', '<= 8'
+  gem.add_runtime_dependency 'activesupport', '>= 4.2'
 
   gem.name = 'hutch'
   gem.summary = 'Opinionated asynchronous inter-service communication using RabbitMQ'