Bump pypa/cibuildwheel from 2.20.0 to 2.21.0

Bumps [pypa/cibuildwheel](https://github.com/pypa/cibuildwheel) from 2.20.0 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@v2.20.0...v2.21.0)

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

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

.github/workflows/ci.yml

@@ -87,7 +87,7 @@ jobs:
           arch: ${{ matrix.arch }}
 
       - name: Build wheels
-        uses: pypa/cibuildwheel@v2.20.0
+        uses: pypa/cibuildwheel@v2.21.0
         env:
           CIBW_TEST_REQUIRES: "coverage pytest pytest-cov"
           CIBW_TEST_COMMAND: "py.test {project}/tests"