update dependencies to streamline compile and reduce audit warnings

[gsfjohnson]

Dependency version changes:

• Update avajs/ava, to use version of fsevents that compiles on node v10 and reduces number of audit warnings.
• Update nodejs/node-gyp, to reduce number of audit warnings.
• Update charto/nbind, to avoid typescript build error.
• Update supported engine versions, due to avajs/ava only supporting node > v8. Also node < v8 are out of maintenance. https://nodejs.org/en/about/releases/