chore(deps): update codecov/codecov-action action to v6 (#923)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
|
[codecov/codecov-action](https://redirect.github.com/codecov/codecov-action)
| action | major | `v5` → `v6` |

---

### Release Notes

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

###
[`v6`](https://redirect.github.com/codecov/codecov-action/compare/v5...v6)

[Compare
Source](https://redirect.github.com/codecov/codecov-action/compare/v5...v6)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
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/JoshuaKGoldberg/ts-api-utils).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0My4xMDIuMTEiLCJ1cGRhdGVkSW5WZXIiOiI0My4xMDIuMTEiLCJ0YXJnZXRCcmFuY2giOiJtYWluIiwibGFiZWxzIjpbImRlcGVuZGVuY2llcyJdfQ==-->

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

Author: renovate[bot]

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
       - run: pnpm run test --coverage
       - if: matrix.node_version == '22.x'
         name: Codecov
-        uses: codecov/codecov-action@v5
+        uses: codecov/codecov-action@v6
         with:
           flags: ${{ matrix.ts_version }}