pybind11 --> nanobind #8

This project (and a few others including https://github.com/danini/magsac) might benefit from using https://github.com/wjakob/nanobind rather than pybind11. I've implemented it in https://github.com/danini/magsac/tree/feat/use-nanobind and it not only is it easier to write the bindings (no need to create a buffer interface to access size and shape), it also allows you to create wheels that use Python's Stable ABI. This means you generate one wheel for 3.12+, reducing build times and allowing us to ship forward compatible wheels (and avoid yearly PRs like danini/magsac#40).