Update train_text_to_image_sdxl.py

[jiagaoxiang]

Enable VAE hash to be able to change with args change. If not, train_dataset_with_embeddings may have row number inconsistency with train_dataset_with_vae. This bug will happen when we change the args. In this situation, train_dataset_with_vae will retrieve the cached data with the old hash value; while train_dataset_with_embeddings will do new calculations with the new hash values. This will cause mismatch.

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Fixes # (issue)

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[linoytsaban]

Thanks @jiagaoxiang! @yiyixuxu should we maybe add a small test here?

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

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[linoytsaban]

@yiyixuxu safe to merge I think?

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