Bump actions/checkout from 3 to 4

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: dependabot[bot] <[email protected]>

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
       with:
         java-version: 11
         distribution: temurin
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: coursier/cache-action@v6
     - run: sbt -v
            "set Test / g8 / g8Properties ~= { _ + (\"scala_version\" -> \"${{ matrix.scala }}\")}"