Update to Scala 3.0.0

[Sorixelle]

Also updates Scalatest to 3.2.9, as 3.2.8 doesn't have a 3.0.0 build.

[lightbend-cla-validator]

Hi @Sorixelle,

Thank you for your contribution! We really value the time you've taken to put this together.

Before we proceed with reviewing this pull request, please sign the Lightbend Contributors License Agreement:

https://www.lightbend.com/contribute/cla

[lxwbr]

@Sorixelle did you have a chance to sign the CLA? I am eagerly waiting for this to be used with scala 3

[sergiuszkierat]

@SethTisue, scala3-migrate raises an error, when can we expect artifacts for 3.0.0?

sbt> migrate-libs root
[info] 
[info] 
[info] Starting to migrate libDependencies for root
[info] 
[info] X             : Cannot be updated to scala 3
[info] Valid         : Already a valid version for Scala 3
[info] To be updated : Need to be updated to the following version
[info] 
[info] com.typesafe.scala-logging:scala-logging:3.9.3           -> X : Contains Macros and is not yet published for 3.0.0

[SethTisue]

@analytically does the publishing around here; you might open an issue requesting a release