deps(deps): update actions/upload-pages-artifact action to v4 (#942)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
|
[actions/upload-pages-artifact](https://redirect.github.com/actions/upload-pages-artifact)
| action | major | `v3` -> `v4` |

---

### Release Notes

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

###
[`v4`](https://redirect.github.com/actions/upload-pages-artifact/compare/v3...v4)

[Compare
Source](https://redirect.github.com/actions/upload-pages-artifact/compare/v3...v4)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - "after 9pm,before 6am" in timezone
Europe/Zurich, Automerge - At any time (no schedule defined).

🚦 **Automerge**: Enabled.

♻ **Rebasing**: Whenever PR is behind base branch, 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

---

This PR was generated by [Mend Renovate](https://mend.io/renovate/).
View the [repository job
log](https://developer.mend.io/github/dotnet/dotnet-operator-sdk).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0MS44MS4yIiwidXBkYXRlZEluVmVyIjoiNDEuODEuMiIsInRhcmdldEJyYW5jaCI6Im1haW4iLCJsYWJlbHMiOlsiZGVwZW5kZW5jaWVzIl19-->

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/gh-pages.yml

@@ -47,7 +47,7 @@ jobs:
         uses: actions/configure-pages@v5
 
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v4
         with:
           path: docs/build