Remove superfluous change

Author: LouiseDck

scgen/_scgenvae.py

@@ -2,7 +2,7 @@
 
 import numpy as np
 import torch
-from scvi._constants import REGISTRY_KEYS
+from scvi import REGISTRY_KEYS
 from scvi.module.base import BaseModuleClass, LossOutput, auto_move_data
 from scvi.nn import Encoder
 from torch.distributions import Normal