Fix vae_encodings_fn hash in train_text_to_image_sdxl.py (#7171)

Update train_text_to_image_sdxl.py

Author: lhoestq

examples/text_to_image/train_text_to_image_sdxl.py

@@ -895,7 +895,7 @@ def preprocess_train(examples):
         # fingerprint used by the cache for the other processes to load the result
         # details: https://github.com/huggingface/diffusers/pull/4038#discussion_r1266078401
         new_fingerprint = Hasher.hash(args)
-        new_fingerprint_for_vae = Hasher.hash("vae")
+        new_fingerprint_for_vae = Hasher.hash(vae_path)
         train_dataset = train_dataset.map(compute_embeddings_fn, batched=True, new_fingerprint=new_fingerprint)
         train_dataset = train_dataset.map(
             compute_vae_encodings_fn,