Fixed AttributeError where openaimodel is not found

Author: smirkingface

modules/sd_hijack.py

@@ -17,6 +17,7 @@
 
 import ldm.modules.attention
 import ldm.modules.diffusionmodules.model
+import ldm.modules.diffusionmodules.openaimodel
 import ldm.models.diffusion.ddim
 import ldm.models.diffusion.plms
 import ldm.modules.encoders.modules