ModuleNotFoundError of timm.models.layers.helpers with timm 0.9.2

[mcollinswisc]

With timm 0.9.2 installed, running the example toolbox.py command, I see an error:

Traceback (most recent call last):
  File "/home/mcollins/repo/external/EfficientFormer/toolbox.py", line 6, in <module>
    from models import *
  File "/home/mcollins/repo/external/EfficientFormer/models/__init__.py", line 1, in <module>
    from .efficientformer import efficientformer_l1, efficientformer_l3, efficientformer_l7
  File "/home/mcollins/repo/external/EfficientFormer/models/efficientformer.py", line 15, in <module>
    from timm.models.layers.helpers import to_2tuple
ModuleNotFoundError: No module named 'timm.models.layers.helpers'

I believe this is due to the changes described at:
https://github.com/huggingface/pytorch-image-models/tree/cd950e6583bd4c5961d88059ff669149d100a1d1#whats-new

timm.models.layers moved to timm.layers

Though I am not sure why the described deprecation mapping doesn't still work for the helpers module.

I see two possible changes that would address this:

1. Update imports of timm.models.layers.helpers to the new location at timm.layers.helpers (and other imports from timm.layers)
2. Specify the version of timm to be < 0.9 in requirements.txt

I could send a PR for either change if desired.