Update third_path path

demo.py

@@ -16,6 +16,7 @@ from detectron2.data.detection_utils import read_image
 from detectron2.utils.logger import setup_logger
 
 sys.path.insert(0, 'third_party/CenterNet2/projects/CenterNet2/')
+sys.path.insert(0, 'third_party/CenterNet2/')
 from centernet.config import add_centernet_config
 from detic.config import add_detic_config