chore: Add updated_at attribute to the conversation event (#10873)

This PR adds updated_at attribute to the conversation event.

spec/models/conversation_spec.rb

@@ -538,6 +538,7 @@ RSpec.describe Conversation do
         contact_last_seen_at: conversation.contact_last_seen_at.to_i,
         agent_last_seen_at: conversation.agent_last_seen_at.to_i,
         created_at: conversation.created_at.to_i,
+        updated_at: conversation.updated_at.to_i,
         waiting_since: conversation.waiting_since.to_i,
         priority: nil,
         unread_count: 0

spec/presenters/conversations/event_data_presenter_spec.rb

@@ -31,6 +31,7 @@ RSpec.describe Conversations::EventDataPresenter do
         contact_last_seen_at: conversation.contact_last_seen_at.to_i,
         agent_last_seen_at: conversation.agent_last_seen_at.to_i,
         created_at: conversation.created_at.to_i,
+        updated_at: conversation.updated_at.to_i,
         waiting_since: conversation.waiting_since.to_i,
         priority: nil,
         unread_count: 0