[e.cash] Bump nodejs version used for deployments

Summary:
Upgrading other dependencies breaks prod deployments due to these dependencies no longer supporting node 16

Update to node 20

Stop linting the lib directory (we do not have a lib directory in this repo...but this causes lint issues during npm run build)

Test Plan: @bot preview-e.cash

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D16483