Fix tokenizer bug (#2573)

### What problem does this PR solve?

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/nlp/rag_tokenizer.py

         self.stemmer = PorterStemmer()
         self.lemmatizer = WordNetLemmatizer()
 
-        self.SPLIT_CHAR = r"([ ,\.<>/?;'\[\]\\`!@#$%^&*\(\)\{\}\|_+=《》，。？、；‘’：“”【】~！￥%……（）——-]+|[a-z\.-]+|[0-9,\.-]+)"
+        self.SPLIT_CHAR = r"([ ,\.<>/?;:'\[\]\\`!@#$%^&*\(\)\{\}\|_+=《》，。？、；‘’：“”【】~！￥%……（）——-]+|[a-z\.-]+|[0-9,\.-]+)"
         try:
             self.trie_ = datrie.Trie.load(self.DIR_ + ".txt.trie")
             return