Fix LiteAgent test mocking: return AgentFinish object instead of raw string

- Mock _invoke_loop to return proper AgentFinish object with output attribute
- This should resolve the 'str' object has no attribute 'output' error in CI

Co-Authored-By: João <joao@crewai.com>

tests/test_integration_llm_features.py

@@ -75,7 +75,9 @@ class TestIntegrationLLMFeatures:
         )
 
         with patch.object(lite_agent, '_invoke_loop') as mock_invoke:
-            mock_invoke.return_value = response_with_xml
+            from crewai.agents.agent_action import AgentFinish
+            mock_agent_finish = AgentFinish(output=response_with_xml, text=response_with_xml)
+            mock_invoke.return_value = mock_agent_finish
             
             result = lite_agent.kickoff("Analyze this problem")