sink.py: fixed CacheEntry import

gstlal/python/pipeparts/sink.py

@@ -8,7 +8,8 @@ import threading
 from typing import Tuple
 
 import numpy
-from lal import LIGOTimeGPS, CacheEntry
+from lal import LIGOTimeGPS
+from lal.utils import CacheEntry
 from ligo import segments
 
 import gi