Fix `isinstance` check in `quat_utils` (#105476)
Calling `isinstance(x, Tuple[Node, Node])` would either fail, or raise a
type error on a more modern Python, as none of the tuples are actually
instances of `Tuple`
```python
>>> from typing import Tuple
>>> from torch.fx import Node
>>> edge_or_node=(Node(None, "foo", "output", "foo", None, None), Node(None, "bar", "output", "bar", None, None))
>>> isinstance(edge_or_node, tuple) and len(edge_or_node) == 2 and all(isinstance(x, Node) for x in edge_or_node)
True
>>> isinstance(edge_or_node, Tuple[Node, Node])
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/malfet/miniconda3/lib/python3.10/typing.py", line 994, in __instancecheck__
return self.__subclasscheck__(type(obj))
File "/Users/malfet/miniconda3/lib/python3.10/typing.py", line 997, in __subclasscheck__
raise TypeError("Subscripted generics cannot be used with"
TypeError: Subscripted generics cannot be used with class and instance checks
```
<!--
copilot:poem
-->
### <samp>🤖 Generated by Copilot at 40fa451</samp>
> _Fix type annotation_
> _Quantize nodes in the graph_
> _Autumn leaves falling_
Pull Request resolved: https://github.com/pytorch/pytorch/pull/105476
Approved by: https://github.com/jerryzh168
