Bump`flash_attn` version to `2.1` (#27079)

* pin FA-2 to `2.1`

* fix on modeling

src/transformers/modeling_utils.py

@@ -1273,15 +1273,15 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin, GenerationMixin, PushToHubMix
 
         if not is_flash_attn_2_available():
             raise ImportError(
-                "Flash Attention 2.0 is not available. Please refer to the documentation of https://github.com/Dao-AILab/flash-attention for"
-                " installing it."
+                "Flash Attention 2 is not available. Please refer to the documentation of https://github.com/Dao-AILab/flash-attention for"
+                " installing it. Make sure to have at least the version 2.1.0"
             )
         else:
             flash_attention_version = version.parse(importlib.metadata.version("flash_attn"))
-            is_flash_greater_than_2 = flash_attention_version > version.parse("2.0.0")
+            is_flash_greater_than_2 = flash_attention_version >= version.parse("2.1.0")
             if not is_flash_greater_than_2:
                 raise ValueError(
-                    f"You need flash_attn package version to be greater than 2.0. Make sure to have that version installed - detected version {flash_attention_version}"
+                    f"You need flash_attn package version to be greater or equal than 2.1. Make sure to have that version installed - detected version {flash_attention_version}"
                 )
 
         _is_bettertransformer = getattr(cls, "use_bettertransformer", False)

src/transformers/utils/import_utils.py

@@ -73,7 +73,7 @@ _apex_available = _is_package_available("apex")
 _bitsandbytes_available = _is_package_available("bitsandbytes")
 _flash_attn_2_available = _is_package_available("flash_attn") and version.parse(
     importlib.metadata.version("flash_attn")
-) >= version.parse("2.0.0")
+) >= version.parse("2.1.0")
 # `importlib.metadata.version` doesn't work with `bs4` but `beautifulsoup4`. For `importlib.util.find_spec`, reversed.
 _bs4_available = importlib.util.find_spec("bs4") is not None
 _coloredlogs_available = _is_package_available("coloredlogs")