[PythonActor] add unhandled exception trace for "_exec_node"

pypushflow/PythonActor.py

@@ -91,6 +91,7 @@ class Edna2Pool(multiprocessing.pool.Pool):
 #############################################################################
 
 
+@trace_unhandled_exceptions
 def _exec_node(name: str, input_: dict, properties: dict):
     """
     Execute a node from the name of the process, input of the process and