Don't filter out `setuptools` in import extractor

[mkniewallner]

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

setuptools is currently filtered out from the list from the import extractor.

As setuptools is mostly a build dependency, there should not be particular reasons to do that. Dependencies that could depend on it exist, but this is also true for other dependencies that are usually installed by default like pip. And even in those cases, dependencies might still explicitly want to specify the dependency explicitly in the dependencies specification, so filtering it out by default doesn't seem like a good thing to do.

Describe the solution you would like

Don't filter out setuptools by default. This probably represents a very few number of libraries, and even in those cases, it would still be possible to use ignore_* settings to filter out the module explicitly, rather than forcing the behaviour on users without any way to opt out of it.