Lazy scipy import (#2250)

python/cutlass/backend/epilogue.py

@@ -34,7 +34,6 @@ import ctypes
 
 from cutlass_library import SubstituteTemplate
 import numpy as np
-from scipy.special import erf
 
 from cutlass_library import DataType, DataTypeTag
 from cutlass.backend.c_types import MatrixCoord_, tuple_factory
@@ -530,6 +529,7 @@ class hardswish(ActivationFunctor, metaclass=hardswishMeta):
 class geluMeta(ActivationMeta):
     @classmethod
     def numpy(cls, x):
+        from scipy.special import erf
         return 0.5 * x * (1 + erf(x / np.sqrt(2.0)))
 
     @classmethod