This adds both Python 3.14 and the experimental free-threaded build to CI. This needs to wait until [PyO3 0.26](https://github.com/PyO3/pyo3/issues/5249) is released. - [ ] Have you followed the guidelines for contributing? - [ ] Have you signed the [CLA](http://www.ubuntu.com/legal/contributors/)? - [ ] Have you successfully run `make lint && make test`? - [ ] Have you added an entry to the changelog (`docs/reference/changelog.rst`)? ---