Fix lint issues in verification script

- Remove unused time import (F401)
- Fix unnecessary f-string without placeholders (F541)

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

verify_thread_safety.py

@@ -6,7 +6,6 @@ Simple verification script for thread safety fix without pytest dependencies.
 import sys
 import os
 import threading
-import time
 from concurrent.futures import ThreadPoolExecutor
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), 'src'))
@@ -86,7 +85,7 @@ def test_thread_safety():
             print(f"✅ Thread safety test passed - each handler received {expected_total} events")
             return True
         else:
-            print(f"❌ Thread safety test failed")
+            print("❌ Thread safety test failed")
             print(f"Handler1 received {len(handler1_events)} events, expected {expected_total}")
             print(f"Handler2 received {len(handler2_events)} events, expected {expected_total}")
             return False