Update src/python/dynamic_queue.py

Author: kelvins

src/python/dynamic_queue.py

@@ -20,7 +20,7 @@ def enqueue(self, val: int) -> None:
             self.__end.next = node
         self.__end = node
 
-    def dequeue(self) -> Node | None:
+    def dequeue(self) -> Node:
         if self.is_empty():
             return None
         node = self.__begin