tests: don't rely on pylint command being available
This is a replay of d5c53373c9fe, accidentally left out in f25542a8833d: Relying on the module's presence is much more reliable, in particular when using MacPorts.
This instance will be upgraded to Heptapod 18.5.1 on 2025-11-13 between 17:00 and 18:00 UTC+2
This is a replay of d5c53373c9fe, accidentally left out in f25542a8833d: Relying on the module's presence is much more reliable, in particular when using MacPorts.