Repoint node-memwatch to fork which supports node 18

[token-cjg]

This change repoints the node-memwatch package dependency to a different fork (@airbnb/node-memwatch) which supports node 18.

Also in this change is a slight implicit change in development tooling to suggest the use of asdf (https://asdf-vm.com/), as well as a quick sweep of security vulnerabilities using npm audit fix --force.

In particular this proposed alteration should address https://github.com/andywer/leakage/issues/34.