Use unit tests in CI setup

[samwillis]

There are a small number of tests in https://github.com/samwillis/nodejs-pypi/tree/main/tests, they test installing packages and executing Node scripts. We should use them in the CI setup.

@jacobdr, any chance you cold add that?

[samwillis]

Just spotted that you have added this in #15:

nodejs-pypi/.github/workflows/test.yaml

Line 39 in d5ba920

python -m pytest