Fix undefined variable in _cast_arguments logging statement

- Replace undefined `function_name` with `getattr(func, '__name__', 'unknown function')`
- This prevents NameError when type casting fails and provides robust function name extraction
- Addresses CodeRabbit review feedback

Co-authored-by: MervinPraison <[email protected]>

Author: claude[bot]

src/praisonai-agents/praisonaiagents/agent/agent.py

@@ -561,7 +561,7 @@ def _cast_arguments(self, func, arguments):
 
             return casted_args
         except Exception as e:
-            logging.debug(f"Type casting failed for {function_name}: {e}")
+            logging.debug(f"Type casting failed for {getattr(func, '__name__', 'unknown function')}: {e}")
             return arguments
 
     def execute_tool(self, function_name, arguments):