kebs-spray-json: support scala 3 about kebs

[luksow]

Hi, there was no plan to support spray-json with Scala 3 as I thought it's not gonna be released but since it's there, I think it should be pretty straightforward to bring it in.

About enumeratum, well I wanted to only have support for proper Scala 3 enums everywhere... Do you think it's good to have that ported, so that the transition is smoother? We might prepare two different packages, one for both Scala 2.13/Scala 3 with enumeratum and one with plain enums only for Scala 3.

Last but not least, I want to stop supporting akka-http in favour of pekko-http, so maybe all these would be a good plan for 2.0.0, cleaning some older mess.

@pjfanning thoughts?

[pjfanning]

@luksow your plan seems ok to me.

I'm not a big user of kebs myself but the utilities it provides are very useful. I use kebs-spray-json in https://github.com/pjfanning/swagger-pekko-http-sample. That currently uses Scala 2.13 but I was considering using Scala 3.