Use core minimum but allow 7.0/7.1/7.2 since core sets upper limit

This should be safe to use as is since the core application sets the rails version.
This will allow us to test with other versions on master.

manageiq-messaging.gemspec

@@ -6,7 +6,7 @@ require 'manageiq/messaging/version'
 Gem::Specification.new do |spec|
   spec.name                  = "manageiq-messaging"
   spec.version               = ManageIQ::Messaging::VERSION
-  spec.required_ruby_version = '>= 2.4'
+  spec.required_ruby_version = '>= 3.1'
   spec.authors               = ["ManageIQ Authors"]
 
   spec.summary       = 'Client library for ManageIQ components to exchange messages through its internal message bus.'
@@ -26,7 +26,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_dependency 'activesupport', '>= 5.2.4.3', "<7.1"
+  spec.add_dependency 'activesupport', '>= 7.0.8', "<8.0"
   spec.add_dependency 'rdkafka', '~> 0.8'
   spec.add_dependency 'stomp', '~> 1.4.4'