Is CUDA 12.8 a hard requirement, or just the dev environment default?

[JunseokLee98]

Hi, thanks for releasing SAM 3!

I noticed that the installation instructions pull flash-attn-3 from the cu128 wheel index, which effectively pins the setup to CUDA 12.8.

Due to infrastructure constraints on my server, I need to reproduce the results with CUDA 12.1 instead.
Before I start debugging dependency issues, I wanted to ask:

• Is CUDA 12.8 required because of a measured performance difference (e.g., a flash-attn-3 feature that isn't available/stable on 12.1),
  or is it simply the environment the model was developed and tested on?

Any guidance would be appreciated. Thanks!