Update the flash-attention submodule (#2500)
Summary:
We need https://github.com/Dao-AILab/flash-attention/pull/1053/files to externally import `flash_attn_interface` for FA3.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/2500
Reviewed By: bertmaher
Differential Revision: D64190441
Pulled By: xuzhao9
fbshipit-source-id: ff20f0a28514b645c828853e7f15808ed1597ae6
