fix: throw warnings if xformers or flash-attn cant be used

modeling_clip.py

@@ -136,7 +136,7 @@ def _resolve_attention_libs(config: JinaCLIPConfig):
             if not torch.cuda.is_available():
                 warnings.warn('Flash attention requires CUDA, disabling')
                 return False
-            if not importlib.util.find_spec('flash_attn') is None:
+            if importlib.util.find_spec('flash_attn') is None:
                 warnings.warn(
                     'Flash attention is not installed. Check '
                     'https://github.com/Dao-AILab/flash-attention?'
@@ -152,7 +152,7 @@ def _resolve_attention_libs(config: JinaCLIPConfig):
             if not torch.cuda.is_available():
                 warnings.warn('xFormers requires CUDA, disabling')
                 return False
-            if not importlib.util.find_spec('xformers') is None:
+            if importlib.util.find_spec('xformers') is None:
                 warnings.warn(
                     'xFormers is not installed. Check '
                     'https://github.com/facebookresearch/xformers?'