Update actions/checkout action to v3 (#54)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://github.com/actions/checkout) | action | major | `v2` -> `v3` |

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### Release Notes

<details>
<summary>actions/checkout</summary>

### [`v3`](https://github.com/actions/checkout/blob/HEAD/CHANGELOG.md#v353)

[Compare Source](actions/checkout@v2...v3)

-   [Fix: Checkout fail in self-hosted runners when faulty submodule are checked-in](actions/checkout#1196)
-   [Fix typos found by codespell](actions/checkout#1287)
-   [Add support for sparse checkouts](actions/checkout#1369)

</details>

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### 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

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This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
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Co-authored-by: Renovate Bot <renovate@minecodes.pl>
Reviewed-on: https://git.minecodes.pl/mineCodes/mineEconomy/pulls/54
Co-authored-by: renovate <renovate@minecodes.pl>
Co-committed-by: renovate <renovate@minecodes.pl>

.github/workflows/main.yml

@@ -8,7 +8,7 @@ jobs:
         java: [8, 11, 16]
     name: Build on JDK ${{ matrix.java }}
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up JDK ${{ matrix.java }}
       uses: actions/setup-java@v2
       with: