chore(deps): Update actions/upload-artifact action to v6 (#2366)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/upload-artifact](https://redirect.github.com/actions/upload-artifact) | action | major | `v5` -> `v6` |

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### Release Notes

<details>
<summary>actions/upload-artifact (actions/upload-artifact)</summary>

### [`v6`](https://redirect.github.com/actions/upload-artifact/compare/v5...v6)

[Compare Source](https://redirect.github.com/actions/upload-artifact/compare/v5...v6)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - Between 12:00 AM and 03:59 AM, on day 1 of the month ( * 0-3 1 * * ) (UTC), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

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 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

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Author: cq-bot

.github/workflows/unittest.yml

@@ -36,7 +36,7 @@ jobs:
         run: echo ${{ github.event.number }} > ./pr_number
       - name: Upload deltas
         if: matrix.os == 'ubicloud-standard-8'
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: delta-action-benchmarks
           retention-days: 7