Migrate away from monix to cats-effect

[mcanlas]

Since monix is no longer maintained, we should upgrade the effect/cancelation framework to cats-effect

Hello from the Scala Spree at Scala Days 2023 Seattle! cc @tgodzik

[He-Pin]

Can it be done with zio or pekko?

[tgodzik]

zio probably also, but pekko would be an even major rewrite, so I would avoid that.

The biggest challenge is to probably use bsp4j first, later we can use any Framework we want underneath

[mcanlas]

I have zero context, so this question might be basic but... What is the relation to bsp4j? Is that somehow tied to this repo's effect system? Or more of architectural debt that would make sense to do first?

[tgodzik]

bsp4s uses monix by default, so to change to cats we can either switch to bsp4j or rewrite bsp4s also to cats. I would prefer the first option since it's more framework agnostic and would be easier to change to something else if needed.