Remove or replace avro4s dependency

[morazow]

Situation

The avro4s project is a macro based library we use to generate Avro schemas of classes at compile time. Unfortunately, we should replace or remove this dependency since it is in maintenance mode only now.

We can't find an replacement, then we may have to write some boilerplate code to generate the Avro schemas. Please note that it is only used in tests.

AC

• Replace or remove the dependency