remove unnecessary JMH dependence

[SethTisue]

this eases adding testz to the Scala 2.12 community build.

something about how sbt-jmh operates confuses dbuild; the easiest way to deal with it is is to confine JMH usage to only subprojects which we can exclude from the community build. but "extras" is depended on by "tests", and obviously we would prefer to include "tests".

it appears to me that the line removed here may be vestigial and not needed anyway.

[SethTisue]

see https://github.com/scala/community-builds/pull/830

[codecov-io]

Codecov Report

:exclamation: No coverage uploaded for pull request base (master@7ff8efd). Click here to learn what that means. The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #31   +/-   ##
=========================================
  Coverage          ?   95.57%           
=========================================
  Files             ?       17           
  Lines             ?      588           
  Branches          ?       23           
=========================================
  Hits              ?      562           
  Misses            ?       26           
  Partials          ?        0

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[NeQuissimus]

@hrhino :)

[SethTisue]

@hrhino are you (or anyone else) merging PRs in this repo, perchance? it's nbd, but it would also be nice to have it out of my queue

[hrhino]

@SethTisue yes; I'll take a look right now. I've been on an OSS moratorium while I get another job's worth of legal issues out of the way, but I'm itching to get back into it.

[SethTisue]

thanks! good luck with the lawyers