Akka test dependencies leaked as runtime dependencies

[pjfanning]

https://github.com/Texera/texera/blob/master/core/amber/build.sbt#L43C1-L44C55

These test dependencies should be 'test' scoped.

I think it is also a bad idea in amber to leak the logback dependency. The point of slf4j is that users choose their own preferred logging implementation. Can this be made a test scoped dependency too?