gstlal_inspiral_plotsummary: Fixed import error

gstlal-inspiral/bin/gstlal_inspiral_plotsummary

@@ -51,6 +51,7 @@ import sys
 from glue import segments
 from glue.ligolw import dbtables
 from glue.ligolw import lsctables
+from glue.ligolw import table
 from glue.ligolw.utils import segments as ligolw_segments
 from glue import lal
 from pylal import db_thinca_rings