Automatic Stub Generation

[Curve]

#74 introduced python stub files which are currently manually generated.

We should adopt some way of automatically generating those stub files either through the pyproject.toml or through the Github-CI, and somehow include them from the pyproject.toml instead of using a shell script

Some references:

• https://github.com/sizmailov/pybind11-stubgen
• https://mypy.readthedocs.io/en/stable/stubgen.html

[tobre1]

I have experienced some issues with mypy stubgen, where some classes are not typed correctly. Therefore I have added the current stub files which I edited manually.

Would be interesting to see if pybind11-stubgen does a better job.