refactor: remove unused JWT imports from utils.py

Author: tomondre

reana_server/utils.py

@@ -703,9 +703,6 @@ def _get_user_from_jwt(header: str) -> User:
     Raises:
         ValueError: If token is invalid or user not found
     """
-    from authlib.jose import jwt, JoseError
-    from authlib.jose.rfc7517.jwk import JsonWebKey
-
     try:
         if not header.startswith('Bearer '):
             raise ValueError("Invalid authorization header format")