Renovate: actions/checkout to v5 (#55)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://redirect.github.com/actions/checkout) |
action | major | `v4` -> `v5` |

---

### Release Notes

<details>
<summary>actions/checkout (actions/checkout)</summary>

### [`v5`](https://redirect.github.com/actions/checkout/compare/v4...v5)

[Compare
Source](https://redirect.github.com/actions/checkout/compare/v4...v5)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - Between 12:00 AM and 03:59 AM, on day
1 of the month ( * 0-3 1 * * ) (UTC), Automerge - Monday through Friday
( * * * * 1-5 ) (UTC).

🚦 **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 was generated by [Mend Renovate](https://mend.io/renovate/).
View the [repository job
log](https://developer.mend.io/github/UCL-ARC/research-software-practices).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0MS4xNTkuNCIsInVwZGF0ZWRJblZlciI6IjQxLjE1OS40IiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6WyJyZW5vdmF0ZSJdfQ==-->

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

Author: renovate[bot]

.github/workflows/link-check.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Link Checker
         id: lychee