revert string conversion

app.py

@@ -69,7 +69,7 @@ def main():
         os.chdir('ppsurf')
 
         print('Inputs:', input_point_cloud_upload)
-        input_shape = str(input_point_cloud_upload)
+        input_shape = input_point_cloud_upload.value
         if not input_shape.endswith('.ply'):
             # load file
             from ppsurf.source.occupancy_data_module import OccupancyDataModule