• (!9) switch to attic in nixpkgs
  
• (!8) improve pushing cache to Gitlab Runner Cache (a bit, it's still slow)
  
• (!7) output to legacyPackages
  
• variables now support containing derivations (these now get evaluated at job runtime instead of "hardcoding" them into the .gitlab-ci.yml)
  
• improve running jobs locally (now correctly includes before_ and after_script and some echoes to see the current step)