fix: fails to check monorepo with non-published packages

[splix]

When you have a monorepo with some of the packages depends on other packages from same project it still tries to download package.json from npm central repo.

It becomes a problem when you have packages that were not published yet, at this case it always fails because it cannot find such package, though it exists locally and is a part of the project. For example if you use it within CI you it will always fail for commits that with new version of a package, unless you publish it before commit.

This PR suggest to skip verification of a dependency when it is another packages in same local project. The package itself will be checked as usual.

[DominicKramer]

Thanks for letting us know about the issue and opening this PR. We really appreciate it. We'll add some tests for your changes.

I also want to double check your changes for the case when the license checker runs on project A that depends on local project B (that has an invalid license). I think the check on A should still fail the license check, but it looks like B would be ignored in your implementation. I'll double check this to see if that is the case.

[splix]

It will be ignores as a dependency verification, but as it's a part of current project it should be checked individually on it's own step.

As I see how it worked:

1. Check package A
2. Check package B as a dependency of A
3. Check package B

My PR eliminates step 2 (because package B may be not published yet and should not be checked against npmjs), but actual check at step 3 should still happen

[DominicKramer]

@splix that makes sense. I've added a test.