update setup.py

csst_ifs_sim/csst_ifs_sim.py

@@ -129,7 +129,7 @@ from csst_ifs_sim.support import cosmicrays
 from csst_ifs_sim.support import logger as lg
 
 
-from CTI import CTI
+from csst_ifs_sim.CTI import CTI
 from optparse import OptionParser
 import configparser as ConfigParser
 import cmath