Unsupported pip interface should not be used, use interface provided by setuptools

[deliciouslytyped]

I've run into an error from

cuckoo/cuckoo/common/utils.py

Line 265 in df55177

for package in pip.get_installed_distributions()

caused by a pip internal api change.

The following issue describes why this is a bad idea and directly provides an alternative in setuptools:
pypa/pip#5243

(anecdotally; on NixOS, downgrading pip gives a version that's not in the binary caches, and results in needing to recompile almost every python dependency involved with Cuckoo, which is reasonable given how NixOS works, it just takes a while.)

[jbremer]

In the latest (unreleased) version of Cuckoo this has been resolved. Thanks for reporting it and thanks to @luis-hebendanz for the fix.