Improve Rails 7.2 compatibility

On trying to upgrade to Rails 7.2, I was experiencing

    [SystemStackError: stack level too deep (SystemStackError)]

On debugging, I found the object triggering this was an instance of
ActiveRecord::Transaction.

Adding this condition in appears to fix the problem.

Author: jamiecobbett

meta_request/lib/meta_request/event.rb

@@ -66,6 +66,7 @@ def sanitize_hash(payload)
 
     def not_encodable?(value)
       return true if defined?(ActiveRecord) && value.is_a?(ActiveRecord::ConnectionAdapters::AbstractAdapter)
+      return true if defined?(ActiveRecord) && defined?(ActiveRecord::Transaction) && value.is_a?(ActiveRecord::Transaction)
       return true if defined?(ActionDispatch) && (value.is_a?(ActionDispatch::Request) || value.is_a?(ActionDispatch::Response))
       return true if defined?(ActionView) && value.is_a?(ActionView::Helpers::FormBuilder)