Update forward method to support TritonServe

Signed-off-by: Jael Gu <mengjia.gu@zilliz.com>

auto_transformers.py

@@ -52,7 +52,8 @@ class Model:
         self.model.eval()
 
     def __call__(self, *args, **kwargs):
-        return self.model(*args, **kwargs)
+        outs = self.model(*args, **kwargs)
+        return outs['last_hidden_state']
 
 
 @register(output_schema=['vec'])
@@ -110,7 +111,7 @@ class AutoTransformers(NNOperator):
             log.error(f'Invalid input for the model: {self.model_name}')
             raise e
         try:
-            features = outs['last_hidden_state'].squeeze(0)
+            features = outs.squeeze(0)
         except Exception as e:
             log.error(f'Fail to extract features by model: {self.model_name}')
             raise e