Updated Python packaging + CI (#146)

This PR introduces various improvements to the python packaging, and adds CI for building cross-platform wheels.

Some new features are:

* Automated python stub generation through `pybind11-stubgen`, which helps with type-hints etc.
* `cibuildwheel` CI for automated building of wheels
* Automated testing through an updated version of `posebench`
* A bunch of minor fixes with the build process
* Some minor fixes to the `python` bindings themselves.

Bump pybind11 and version (#105)

Bumps the pybind11 version to the latest. There seem to be some segfault issues that are resolved in this version. Also bump the version number to 2.0.4.

Added decompositions for focal lengths from F (#102)

Added fundamental matrix decompositions (extracting focal lengths) from Kocur et al. CVPR 2024