Change scope for jmh dependencies

[ClaasJG]

Hi,

currently, clipper2-java leaks jmh-core and jmh-generator-annprocess when consuming it via jitpack.io.
Both dependencies are only required for the JMH benchmarks. Based on the readme of the used jmh plugin

This plugin does not generate the uber-jar as is usual with the default JMH approach. It instead just invokes the benchmark with the test classpath.

which means, that those dependencies can use the test scope.

Thanks for the port and have a nice day

-ClaasJG