Fix camera_calibration when selecting fisheye ros2 galactic (#769)

When you choose the fisheye camera type the calibration script crashes

camera_calibration/src/camera_calibration/camera_calibrator.py

@@ -42,7 +42,7 @@
 import sensor_msgs.srv
 import threading
 import time
-from camera_calibration.calibrator import MonoCalibrator, StereoCalibrator, ChessboardInfo, Patterns
+from camera_calibration.calibrator import MonoCalibrator, StereoCalibrator, ChessboardInfo, Patterns, CAMERA_MODEL
 from collections import deque
 from message_filters import ApproximateTimeSynchronizer
 from std_msgs.msg import String