[shardformer] import huggingface implicitly (#4101)

colossalai/shardformer/policies/t5.py

@@ -1,15 +1,4 @@
-from transformers import T5ForConditionalGeneration
-from transformers.models.t5.modeling_t5 import (
-    T5Attention,
-    T5DenseActDense,
-    T5DenseGatedActDense,
-    T5LayerCrossAttention,
-    T5LayerFF,
-    T5LayerSelfAttention,
-    T5Stack,
-)
-
-from colossalai.shardformer.layer import DropoutForParallelInput, Embedding1D, FusedRMSNorm, Linear1D_Col, Linear1D_Row
+from colossalai.shardformer.layer import DropoutForParallelInput, Embedding1D, Linear1D_Col, Linear1D_Row
 
 from .basepolicy import ModulePolicyDescription, Policy, SubModuleReplacementDescription
 
@@ -34,7 +23,17 @@ class T5ModelPolicy(Policy):
         return self.model
 
     def module_policy(self):
-        base_policy = {
+        from transformers.models.t5.modeling_t5 import (
+            T5Attention,
+            T5DenseActDense,
+            T5DenseGatedActDense,
+            T5LayerCrossAttention,
+            T5LayerFF,
+            T5LayerSelfAttention,
+            T5Stack,
+        )
+
+        return {
             T5Stack:
                 ModulePolicyDescription(attribute_replacement={},
                                         param_replacement=[],
@@ -165,6 +164,8 @@ class T5ModelPolicy(Policy):
 class T5ForConditionalGenerationPolicy(T5ModelPolicy):
 
     def module_policy(self):
+        from transformers import T5ForConditionalGeneration
+
         policy = super().module_policy()
 
         new_item = {