Remove devel/ruby-jeweler

In preparation for making Ruby 2.7 the default Ruby version in ports, I
would like to remove devel/ruby-jeweler. It currently doesn't build
with Ruby 2.7 as Ruby 2.7 includes Bundler 2, and the ports version of
jeweler is 8 years old and only supports Bundler 1. We could consider
upgrading to the current version of jeweler (2.3.9), but that would
require importing at least 3 new ports.

jeweler was only used as a test dependency on 5 other ports, it was not
a build or runtime dependency of any ports. I've already removed the
test dependency in the 5 other ports, 2 of which had broken tests, 2 of
which were fine without the jeweler test dependency, and 1 of which
required a one line patch.

jeweler is dead upstream, there is a similar newer project named
juweiler by the same maintainer, which also hasn't seen a release since
January 2018. The purpose of both jeweler and juweiler is to automate
simple tasks like version bumping and releasing new versions.

OKs to remove devel/ruby-jeweler?

Thanks,
Jeremy