[gh-actions]: Bump actions/checkout from 3 to 4 (#28)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: Ryuu Mitsuki <[email protected]>
Authored-by: dependabot[bot] <[email protected]>
Co-authored-by: Ryuu Mitsuki <[email protected]>

.github/workflows/irltest.yml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Setup Node.js / ${{ matrix.node-ver }}
       uses: actions/setup-node@v4
       with: