Bump actions/upload-artifact from 5 to 6

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v5...v6)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/test.yml

@@ -50,7 +50,7 @@ jobs:
       if: ${{matrix.ruby == needs.ruby-versions.outputs.latest || matrix.upload}}
       shell: bash
     - name: Upload package
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         path: pkg/*
         name: ${{steps.build.outputs.pkg}}