deps: update codecov/codecov-action action to v4 (#359)

[![Mend
Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [codecov/codecov-action](https://togithub.com/codecov/codecov-action)
| action | major | `v3` -> `v4` |

---

### Release Notes

<details>
<summary>codecov/codecov-action (codecov/codecov-action)</summary>

### [`v4`](https://togithub.com/codecov/codecov-action/compare/v3...v4)

[Compare
Source](https://togithub.com/codecov/codecov-action/compare/v3...v4)

</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

---

This PR has been generated by [Mend
Renovate](https://www.mend.io/free-developer-tools/renovate/). View
repository job log
[here](https://developer.mend.io/github/hetznercloud/hcloud-python).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzNy4xNTMuMiIsInVwZGF0ZWRJblZlciI6IjM3LjE1My4yIiwidGFyZ2V0QnJhbmNoIjoibWFpbiJ9-->

---------

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

Author: renovate[bot]

.github/workflows/test.yml

@@ -29,4 +29,6 @@ jobs:
         run: tox -- --cov --cov-report=xml
 
       - name: Upload coverage reports to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}