Bump actions/upload-artifact from 5 to 6 (#231)

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
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/wheels.yml

@@ -135,7 +135,7 @@ jobs:
         run: |
           python -m cibuildwheel --output-dir wheelhouse
 
-      - uses: actions/upload-artifact@v5
+      - uses: actions/upload-artifact@v6
         with:
           name: wheels_cp${{ matrix.python }}-${{ matrix.builder }}_${{ matrix.arch }}
           path: ./wheelhouse/so3g*cp${{ matrix.python }}-${{ matrix.builder }}*${{ matrix.arch }}*.whl