Sttp - usability and stability for 1.0

[szymon-rd]

Context

This issue is meant to track the progress in improving the toolkit libraries' usability and stability. This issue is created here to establish the toolkit's perspective in the discussion, especially the interoperability between the toolkit's libraries and usability with the definition used in the Toolkit.

Tasks

Below is the list of high-priority issues. They all should have corresponding issues in the library's issue tracker when we start working on them. The discussions about the usability of the library within the Toolkit should take place here.

• [x] BodySerializer for ujson's Json type - https://github.com/softwaremill/sttp/issues/1862
• [x] Integration with os-lib and/or geny - https://github.com/softwaremill/sttp/issues/1822
• [x] Release 4.0.0

[SethTisue]

We had a language newcomer and toolkit user on Discord today get thoroughly confused by the sttp 3 vs 4 issue today.

Eager to see sttp 4 get out of the milestones stage.