Bump actions/upload-artifact from 3 to 4

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v3...v4)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/gradle.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Collect mutation testing report
         run: mkdir mutation-testing-report && cp -r build/reports/pitest/* mutation-testing-report
       - name: Archive mutation testing results
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: mutation-testing-report-${{ matrix.java }}
           path: mutation-testing-report