Update https://github.com/actions/upload-artifact action to v7 (#7)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [https://github.com/actions/upload-artifact](https://github.com/actions/upload-artifact) | action | major | `v6` → `v7` |

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### Release Notes

<details>
<summary>actions/upload-artifact (https://github.com/actions/upload-artifact)</summary>

### [`v7`](https://github.com/actions/upload-artifact/compare/v6...v7)

[Compare Source](https://github.com/actions/upload-artifact/compare/v6...v7)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), 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.

---

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

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This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
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Reviewed-on: #7
Co-authored-by: Renovate Bot <renovate@keligrubb.com>
Co-committed-by: Renovate Bot <renovate@keligrubb.com>

.gitea/workflows/release.yml

@@ -33,7 +33,7 @@ jobs:
         run: npm start
 
       - name: Upload PDF artifact
-        uses: https://github.com/actions/upload-artifact@v6
+        uses: https://github.com/actions/upload-artifact@v7
         with:
           name: release-pdf
           path: "*.pdf"