Fix: retrieval debug mode issue. (#6150)

### What problem does this PR solve?

#6139

### Type of change

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

deepdoc/parser/pdf_parser.py

@@ -41,6 +41,7 @@ LOCK_KEY_pdfplumber = "global_shared_lock_pdfplumber"
 if LOCK_KEY_pdfplumber not in sys.modules:
     sys.modules[LOCK_KEY_pdfplumber] = threading.Lock()
 
+
 class RAGFlowPdfParser:
     def __init__(self, parallel_devices: int | None = None):
         """