Update tests/test_cube3d.py, tests/test_map2d.py, tests/test_spec1d.py

tests/test_cube3d.py

 import sys
 sys.path.insert(0, '..')
 import unittest
-from gehong import spec1d as s
-from gehong import map2d as m
-from gehong import cube3d as b
-from gehong import config as c
+from csst_ifs_gehong import spec1d as s
+from csst_ifs_gehong import map2d as m
+from csst_ifs_gehong import cube3d as b
+from csst_ifs_gehong import config as c
 import numpy as np
 import matplotlib.pyplot as plt
 

tests/test_map2d.py

 import sys
 sys.path.insert(0, '..')
 import unittest
-from gehong import map2d as m
-from gehong import config as c
+from csst_ifs_gehong import map2d as m
+from csst_ifs_gehong import config as c
 import numpy as np
 import matplotlib.pyplot as plt
 

tests/test_spec1d.py

 import sys
 sys.path.insert(0, '..')
 import unittest
-from gehong import spec1d as s
-from gehong import config as c
+from csst_ifs_gehong import spec1d as s
+from csst_ifs_gehong import config as c
 import numpy as np
 import matplotlib.pyplot as plt