Fix CI problems

[oyyd]

Currently, tests always fail because:

1. The action mmarchini/setup-node@mirror uses a deprecated add-path command

Rebasing the upstream code should fix this, like: mmarchini/setup-node#1

2. Install liblldb-3.9-dev on ubuntu-latest, that is ubuntu-20.04 now, would fail:

Don't know why but indicating ubuntu-18.04 should fix this.

[No9]

Fixed in #398

[No9]

#398 landed in main so closing this.
Thanks for reporting