fix: uuid not import bug

[yihong0618]

Summary

still found by https://github.com/langgenius/dify/pull/10921 and part of it. the uuid did not import and it will always into the except part

code in line 186

...
                    try:
                        uuid.UUID(tool_item["id"])
                    except ValueError:
                        raise ValueError("id in dataset must be of UUID type")

                    if not cls.is_dataset_exists(tenant_id, tool_item["id"]):
                        raise ValueError("Dataset ID does not exist, please check your permission.")

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Screenshots

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Checklist

[!IMPORTANT]
Please review the checklist below before submitting your pull request.

• [ ] This change requires a documentation update, included: Dify Document
• [x] I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• [x] I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• [x] I've updated the documentation accordingly.
• [x] I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods