update test data for node 18 lts release

[ryenus]

lts/gallium is node 16, while lts/hydrogen is node 18.

This fixes the following test:

• nvm_list_aliases works with LTS aliases

[ryenus]

Just to get the CI working first, I don't think it's a good test though.

[ljharb]

This will fail, because Travis is on xenial which can’t build node 18. If you can help install the right C libs on Xenial, that would unblock this :-)

[ryenus]

This will fail, because Travis is on xenial which can’t build node 18. If you can help install the right C libs on Xenial, that would unblock this :-)

Hmmm, that's way more than I had expected, not sure if I could figure that out but I think that will require a separate PR or something?

[ljharb]

I think this PR should end up containing that fix. It's definitely a much larger change.

[ljharb]

I've updated this with a commit that runs the "update test mocks" script (and fixed tests on master)