chore(deps): update actions/checkout action to v4 (#19)

This PR contains the following updates:

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

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### Release Notes

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

### [`v4`](https://github.com/actions/checkout/blob/HEAD/CHANGELOG.md#v400)

[Compare Source](https://github.com/actions/checkout/compare/v3...v4)

-   [Support fetching without the --progress option](https://github.com/actions/checkout/pull/1067)
-   [Update to node20](https://github.com/actions/checkout/pull/1436)

</details>

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### Configuration

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🚦 **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.

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Reviewed-on: https://gitea.com/gitea/terraform-provider-gitea/pulls/19
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Co-committed-by: Renovate Bot <renovate-bot@gitea.com>

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
       -
         name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       -
         name: Unshallow
         run: git fetch --prune --unshallow