Support process.hrtime.bigint()

[abrenneke]

It would be useful if this module also supported hrtime.bigint().

If you do

const start = process.hrtime.bigint();
prettyTime(process.hrtime.bigint() - start);

You'll get a

TypeError: Cannot mix BigInt and other types, use explicit conversions
    at module.exports (pretty-time/index.js:32:19)

So it's neccesary to do prettyTime(Number(process.hrtime.bigint() - start)) - would be nice it this module did that itself.

[TheOptimisticFactory]

Moreover, process.hrtime([time]) has been deprecated, leaving process.hrtime.bigint() the only option for now:

See: https://nodejs.org/api/process.html#process_process_hrtime_time