docutils: docutils.nodes.Node.next_node can return None (#14833)

Author: adamtheturtle

stubs/docutils/docutils/nodes.pyi

@@ -89,7 +89,7 @@ class Node:
     @overload
     def next_node(
         self, condition: type[_N], include_self: bool = False, descend: bool = True, siblings: bool = False, ascend: bool = False
-    ) -> _N: ...
+    ) -> _N | None: ...
     @overload
     def next_node(
         self,
@@ -98,7 +98,7 @@ class Node:
         descend: bool = True,
         siblings: bool = False,
         ascend: bool = False,
-    ) -> Node: ...
+    ) -> Node | None: ...
     def validate(self, recursive: bool = True) -> None: ...
     def validate_position(self) -> None: ...