Motivation / Background

github.com/gogo/protobuf is deprecated and doesn't work with newer protobuf files. It's time to switch to standard protobuf.

Detail

It's important that this change won't affect services that are using the old marshaled.
Unfortunately, gogo protobuf doesn't handle messages generated by newer protobuf (it even panics).
To allow simple migration, in the old marshaled, I added an optional fallback (enabled by default) to github.com/golang/protobuf/proto when gogo failed to marshal/unmarshal message.
Thanks to that, it's possible to create a two-step migration:

1. Updating all publishers and subscribers Watermill (so forward compatibility will be added) - no code change required
2. Updating to the non-deprecated marshaler.

Checklist

The resources of our team are limited. There are a couple of things that you can do to help us merge your PR faster:

• I wrote tests for the changes.
• All tests are passing.
  • If you are testing a Pub/Sub, you can start Docker with make up.
  • You can start with make test_short for a quick check.
  • If you want to run all tests, use make test.
• Code has no breaking changes.
• (If applicable) documentation on watermill.io is updated.
  • Documentation is built in the github.com/ThreeDotsLabs/watermill/docs.
  • You can find development instructions in the DEVELOP.md.