auxcache.py: forgot to change multichannel_datasource import after move to burst

gstlal-burst/python/fxtools/auxcache.py

@@ -42,7 +42,7 @@ Gst.init(None)
 from gstlal import datasource
 from gstlal import pipeparts
 from gstlal import simplehandler
-from gstlal import multichannel_datasource
+from gstlal.fxtools import multichannel_datasource
 
 #
 # =============================================================================