Remove type hints from arxiv_fetch.py

- Removed type hints from normalize_license_text function
- Type checkers not yet used as tooling for the project

Author: Goziee-git

scripts/1-fetch/arxiv_fetch.py

@@ -248,7 +248,7 @@ def get_requests_session():
     return session
 
 
-def normalize_license_text(raw_text: str) -> str:
+def normalize_license_text(raw_text):
     """Normalize license text to standard CC license identifiers."""
     if not raw_text:
         return "Unknown"