restore package.json version export (using import attributes)

[thescientist13]

As part of the initial first pass of ESM support via #1 , one thing that is being withheld is the exporting of the version field from package.json.

# re-written for ESM <> import attributes
import packageJson from './package.json' assert { type: 'json' };

Mainly because Rollup doesn't support them yet, and that's what Greenwood uses 🤠