Remove redundant stack copies after execution

The input stack is already copied when remember_stack is off, and the
removed line is a no-op when it is on.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

more_math/ImageMathNode.py

@@ -159,8 +159,6 @@ class ImageMathNode(io.ComfyNode):
             res_list = []
             for result_chunk in res:
                 res_list.append(result_chunk)
-            stack = stack if remember_stack else copy.deepcopy(stack)
             return (res_list, stack)
         else:
-            stack = stack if remember_stack else copy.deepcopy(stack)
             return ([result], stack)