Updated Akka-related dependencies.
Updated Akka-related dependencies.

Akka 2.6.14 -> 2.6.15
Jackson 2.12.2 -> 2.12.4
Aeron 1.32.0 -> 1.34.0
SslConfigCore 0.4.2 -> 0.4.3

This fixes the version conflicts, and the tests can again be executed
successfully.

oheger/LineDJ