Fix Python 3.10 compatibility: Replace datetime.UTC with timezone.utc

- Created datetime_compat module to provide UTC constant using timezone.utc
- Updated all direct UTC imports to use compatibility module
- Added tests to verify UTC timezone compatibility
- Fixes #2171

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

tests/traces/test_unified_trace_controller.py

@@ -1,5 +1,5 @@
 import os
-from datetime import UTC, datetime
+from datetime import datetime
 from unittest.mock import MagicMock, patch
 from uuid import UUID
 
@@ -21,6 +21,7 @@ from crewai.traces.unified_trace_controller import (
     trace_flow_step,
     trace_llm_call,
 )
+from crewai.utilities.datetime_compat import UTC
 
 
 class TestUnifiedTraceController: