another py3 fix

Author: fchapoton

scripts.dtx

@@ -216,7 +216,7 @@ See the SageTeX documentation for more details.""" % sys.argv[0])
 
 try:
   opts, args = getopt.getopt(sys.argv[1:], 'ho', ['help', 'overwrite'])
-except getopt.GetoptError, err:
+except getopt.GetoptError as err:
   print(str(err))
   usage()
   sys.exit(2)