v3.0.0

• Use repr to represent all JSON fields of unknown types by
  default. Previously, when passing a mapping (dictionary) as a log
  message, watchtower would replace datetime objects with their
  ".isoformat()" string representation, and would replace all other
  non-JSON-serializable objects with null. The new behavior is to
  use the output of repr() to represent these non-JSON-serializable
  objects. This change may cause your logger to log more data than you
  intended, which is why it triggers a major version bump. If you use
  watchtower to log sensitive information or objects with large repr
  strings, you are advised to examine your log messages to see if any
  newly visible data should be sanitized. If you need to customize
  this behavior, you can pass a custom JSON default serializer using
  the json_serialize_default keyword argument.