Regression Proximal Causal Inference

[pzivich]

Is your feature request related to a problem? Please describe.

Add a general implementation of proximal CI to causal.py.

Describe the solution you'd like

There is a general implementation of proximal CI using GLM's. This would be good to include as an option.

Describe alternatives you've considered

None.

Additional context

Reference: https://arxiv.org/abs/2402.00335