[to #42322933] remove sep token at the end of tokenizer output

generate 时去除 tokenizer 输出结尾的 sep，修复 gpt3 模型目前续写内容与上文无关的 bug
        Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/9696570

modelscope/models/nlp/gpt3/gpt3_for_text_generation.py

@@ -48,6 +48,8 @@ class GPT3ForTextGeneration(TorchModel):
             attention_mask = input['attention_mask']
             input_ids = input_ids[0][attention_mask[0].nonzero()] \
                 .squeeze().unsqueeze(0)
+        # remove sep token at the end of tokenizer output
+        input_ids = input_ids[:, :-1]
 
         gen_params = dict()
         gen_params['inputs'] = input_ids

tests/pipelines/test_text_generation.py

@@ -32,7 +32,7 @@ class TextGenerationTest(unittest.TestCase):
 
         self.gpt3_base_model_id = 'damo/nlp_gpt3_text-generation_chinese-base'
         self.gpt3_large_model_id = 'damo/nlp_gpt3_text-generation_chinese-large'
-        self.gpt3_input = '我很好奇'
+        self.gpt3_input = '《故乡》。深蓝的天空中挂着一轮金黄的圆月，下面是海边的沙地，'
 
     def run_pipeline_with_model_instance(self, model_id, input):
         model = Model.from_pretrained(model_id)