Enhance annotation for Graph.add_weighted_edges_from

Enhance annotation for `Graph.add_weighted_edges_from`

The current 
[`3.6.1.20260303`](https://github.com/python/typeshed/blob/50ec9108eb191ab96d9ab766e506a7c680d5f3d6/stubs/networkx/networkx/classes/graph.pyi#L74) textual
description states:

> ebunch_to_add: container of edges
>Each edge given in the list or container will be added to the 
> graph.
> The edges must be given as 3-tuples (u, v, w) where w is a 
> number.

However

1. `w` can be a `Decimal` (which is still a number) or
2. even `None` (which is not a number), but the used
    `add_edges_from` and `add_edges` methods process it fine.

Change the annotation to reflect these.

Author: GBognar

stubs/networkx/networkx/classes/graph.pyi

@@ -1,4 +1,5 @@
 from collections.abc import Callable, Collection, Hashable, Iterable, Iterator, MutableMapping
+from decimal import Decimal
 from functools import cached_property
 from typing import Any, ClassVar, TypeVar, overload
 from typing_extensions import Self, TypeAlias
@@ -71,7 +72,7 @@ class Graph(Collection[_Node]):
     def add_edges_from(self, ebunch_to_add: Iterable[_EdgePlus[_Node]], **attr: Any) -> None: ...
     # attr: Edge data (or labels or objects) can be assigned using keyword arguments
     def add_weighted_edges_from(
-        self, ebunch_to_add: Iterable[tuple[_Node, _Node, float]], weight: str = "weight", **attr: Any
+        self, ebunch_to_add: Iterable[tuple[_Node, _Node, float|Decimal|None]], weight: str = "weight", **attr: Any
     ) -> None: ...
     # attr: Edge attributes to add/update for all edges.
     def remove_edge(self, u: _Node, v: _Node) -> None: ...