New API for pyfixest 0.17.0

[s3alfisc]

Hi Arthur, @Wenzhi-Ding and I have updated the pyfixest API, which we will release with pyfixest 0.17.0. It should be more user-friendly and also helps us with keeping the repo in order. The changes are minimal and I think I have caught all places in CfE where pyfixest is called. I'll update you here once version 0.17.0 is released. The changes are non-breaking, so there is no need to upgrade immediately.

With the new API, a pyfixest workflow would look like this:

import pyfixest as pf
data = pf.get_data()
fit = pf.feols("Y ~ X1", data = data)
pf.etable([fit])

In this PR, I have updated the regression chapter to reflect these changes and changed the required pyfixest version to 0.17.0.

[aeturrell]

This is brilliant—thanks for making it super super easy for me @s3alfisc. I like the API changes too.