Include appleseed-metric in package.json

[RangerMauve]

Getting an error when trying to use trustnet:

Error: Cannot find module 'appleseed-metric'
Require stack:
- /home/mauve/programming/ushin-db/node_modules/trustnet/trustnet.js
- /home/mauve/programming/ushin-db/node_modules/trustnet/index.js
- /home/mauve/programming/ushin-db/USHINBase.js
- /home/mauve/programming/ushin-db/source.js
- /home/mauve/programming/ushin-db/test/test.js
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:919:15)
    at Function.Module._load (node:internal/modules/cjs/loader:763:27)
    at Module.require (node:internal/modules/cjs/loader:991:19)
    at require (node:internal/modules/cjs/helpers:92:18)
    at Object.<anonymous> (/home/mauve/programming/ushin-db/node_modules/trustnet/trustnet.js:2:19)
    at Module._compile (node:internal/modules/cjs/loader:1102:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1131:10)
    at Module.load (node:internal/modules/cjs/loader:967:32)
    at Function.Module._load (node:internal/modules/cjs/loader:807:14)
    at Module.require (node:internal/modules/cjs/loader:991:19) {
  code: 'MODULE_NOT_FOUND',
  requireStack: [
    '/home/mauve/programming/ushin-db/node_modules/trustnet/trustnet.js',
    '/home/mauve/programming/ushin-db/node_modules/trustnet/index.js',
    '/home/mauve/programming/ushin-db/USHINBase.js',
    '/home/mauve/programming/ushin-db/source.js',
    '/home/mauve/programming/ushin-db/test/test.js'
  ]
}

Would a PR that adds appleseed-metric to the dependencies be welcome?

[cblgh]

foixed