[to #41474818]fix: fix errors in task name definition

修改constant.py中task name定义的错误
- sentence-similarity重复定义
- fill-mask多加了一个空格
        Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/9125956

    * [to #41474818]fix: fix errors in task name definition

modelscope/utils/constant.py

@@ -43,8 +43,7 @@ class Tasks(object):
     text_generation = 'text-generation'
     table_question_answering = 'table-question-answering'
     feature_extraction = 'feature-extraction'
-    sentence_similarity = 'sentence-similarity'
-    fill_mask = 'fill-mask '
+    fill_mask = 'fill-mask'
     summarization = 'summarization'
     question_answering = 'question-answering'