make it work with batch_sie >1

Author: yiyixuxu

src/diffusers/models/transformers/transformer_wan.py

@@ -324,7 +324,7 @@ def forward(
     ):
         timestep = self.timesteps_proj(timestep)
         if timestep_seq_len is not None:
-            timestep = timestep.unflatten(0, (1, timestep_seq_len))
+            timestep = timestep.unflatten(0, (-1, timestep_seq_len))
 
         time_embedder_dtype = next(iter(self.time_embedder.parameters())).dtype
         if timestep.dtype != time_embedder_dtype and time_embedder_dtype != torch.int8: