Remove linting from 'test' npm script

[romaricpascal]

I found tests being prevented to run by linting errors that would be fixed on commit quite annoying during development, as it forces you to fix formatting issue before getting feedback on whether your changes work OK from a functional standpoint.

Linting will run on commit and CI (in parallel to tests there) to pick on formatting errors, so formatting issues will not slip through even if they are not checked by the test script.