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/release-wheels.yml

@@ -19,7 +19,7 @@ jobs:
       - run: pip install setuptools wheel
       - name: Build wheels
         run: python setup.py bdist_wheel
-      - uses: actions/upload-artifact@v5
+      - uses: actions/upload-artifact@v6
         with:
           path: dist/*.whl
           name: artifact-wheels
@@ -36,7 +36,7 @@ jobs:
       - run: pip install setuptools
       - name: Build sdist
         run: python setup.py sdist
-      - uses: actions/upload-artifact@v5
+      - uses: actions/upload-artifact@v6
         with:
           path: dist/*.tar.gz
           name: artifact-sdist