FACEMESH_TESSELATION으로 바꿔주었더니 정상출력 되었다.
I just looked into the sourcecode at https://github.com/google/mediapipe/blob/master/mediapipe/python/solutions/holistic.py
FACE_CONNECTIONS seems to be renamed/replaced by FACEMESH_TESSELATION.
Just changing that name in the code should work.
PS: If you want just the outlines of the face, it's now FACEMESH_CONTOURS