set the model to train state before accelerator prepare (#5099)

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

examples/textual_inversion/textual_inversion.py

@@ -761,6 +761,7 @@ def main():
         num_cycles=args.lr_num_cycles,
     )
 
+    text_encoder.train()
     # Prepare everything with our `accelerator`.
     text_encoder, optimizer, train_dataloader, lr_scheduler = accelerator.prepare(
         text_encoder, optimizer, train_dataloader, lr_scheduler