6.0.0 Release candidate

A lot has changed! Loki has got a new push endpoint since the last release, and there's some changes to the data model as well on their end.

This was a bit larger update than I thought, and the tests are still unfortunately lagging behind. All things should work, and I've tested both the JSON and Protobuf side of things locally with a Loki instance.

There's also a new directory, ./examples/! If you want to get a head start on how to use winston-loki, please check that out for a fast test configuration of Grafana+Loki+Promtail and run the examples with node.

Because the thing works though the tests don't, I'll release this under the @next tag in npm. If you want to take a deep dive in Node.js testing world, please take a look at the tests. I'll try to fix them myself whenever I have more time on my hands.

Thanks to all that have contributed to the library so far, you've been indispensable!