Default to APT solver version 3

Today I learned, that Debian still does not default to the new solver¹ - for reasons unknown I have assumed it's already used out of the box.

As I want to avoid having to think about it or adjust aliases again, I decided to configure it in APT's configuration²

/etc/apt/apt.conf.d/90solver:

binary::apt::APT::Solver "3.0";