Fix: delimiter issue. (#5720)

### What problem does this PR solve?

#5704

### Type of change

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

deepdoc/parser/txt_parser.py

@@ -31,6 +31,7 @@ class RAGFlowTxtParser:
             raise TypeError("txt type should be str!")
         cks = [""]
         tk_nums = [0]
+        delimiter = delimiter.encode('utf-8').decode('unicode_escape').encode('latin1').decode('utf-8')
 
         def add_chunk(t):
             nonlocal cks, tk_nums, delimiter