Bump pypa/cibuildwheel from 2.17.0 to 2.21.0

Bumps [pypa/cibuildwheel](https://github.com/pypa/cibuildwheel) from 2.17.0 to 2.21.0.
- [Release notes](https://github.com/pypa/cibuildwheel/releases)
- [Changelog](https://github.com/pypa/cibuildwheel/blob/main/docs/changelog.md)
- [Commits](pypa/cibuildwheel@v2.17.0...v2.21.0)

---
updated-dependencies:
- dependency-name: pypa/cibuildwheel
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

.github/workflows/pythonpackage.yml

@@ -59,7 +59,7 @@ jobs:
       uses: docker/setup-qemu-action@v3.2.0
       if: runner.os == 'Linux' && matrix.use_qemu
     - name: Build wheels
-      uses: pypa/cibuildwheel@v2.17.0
+      uses: pypa/cibuildwheel@v2.21.0
       with:
         package-dir: helics_apps-pip
       env: