Not support pytorch _1.3.1

[huangnengCSU]

To developer: Thank you for developing such a grateful optimizer. I have used it with pytorch_1.8 and pytorch_1.9 successfully. When I use the pytorch_1.3.1, ranger21 reports some errors. I think ranger21 not support pytorch_1.3.1. Could you make it available in the feature, please? Here is the report info:

import torch
import ranger21
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/home/huangneng/tools/Ranger21/ranger21/__init__.py", line 1, in <module>
   from .ranger21 import Ranger21
 File "/home/huangneng/tools/Ranger21/ranger21/ranger21.py", line 49, in <module>
   from torch import linalg as LA
ImportError: cannot import name 'linalg'

Best, Neng