[networkx] Fix argument type of node_connected_component (#13612)

Author: kyllb

stubs/networkx/networkx/algorithms/components/connected.pyi

@@ -11,4 +11,4 @@ def number_connected_components(G: Graph[_Node]): ...
 @_dispatchable
 def is_connected(G: Graph[_Node]): ...
 @_dispatchable
-def node_connected_component(G: Graph[_Node], n: str): ...
+def node_connected_component(G: Graph[_Node], n: _Node): ...