pom.xml:196: Activate JMH for testing on JDK8

[0pdd]

The puzzle DEV-5f4df571 from #DEV has to be resolved:

https://github.com/dgroup/enumerable4j/blob/373ea3416dae428b40bd3adfefb4c0f847807ab0/pom.xml#L196-L196

The puzzle was created by @dgroup on 06-Mar-21.

role: DEV.

If you have any technical questions, don't ask me, submit new tickets instead. The task will be "done" when the problem is fixed and the text of the puzzle is removed from the source code. Here is more about PDD and about me.