Add flux executor shutdown

executorlib/interactive/flux.py

@@ -100,6 +100,9 @@ def shutdown(self, wait: bool = True):
         # still showing running after cancel was called,
         # so we wait until the execution is completed.
         self._future.result()
+        # shutdown flux executor
+        if self._flux_executor is not None:
+            self._flux_executor.shutdown(wait=wait)
 
     def poll(self):
         """