Add Python 3.12 support

[nicholasjng]

These commits contain a few changes:

• nanobind bump to v1.6.2 (Sep 2023). (0a816f05653eada761d6a3caf6daa34822f02ad7)
• GitHub Actions checkout to v4, reset to windows-latest as Windows runner image. (609415eee9a21b4a9b7653eb2503df08b38fae80)
• Python 3.12 wheel builds via cibuildwheel version bump and envvar change. (609415eee9a21b4a9b7653eb2503df08b38fae80)
• The move to trusted publishing for PyPI wheel releases. (609415eee9a21b4a9b7653eb2503df08b38fae80)

Related: I am currently working on a project using setuptools_scm as an addition in the build step, which makes manual version bumping for the Python bindings unnecessary (the package parses the new version out of a tag name created e.g. by a GitHub release), in case there is interest in opting into that.

[nicholasjng]

Rebased on main, bumped nanobind to stable v1.7.0, which was released in the meantime.