[ANN] ZenTest 4.12.0 Released

ZenTest version 4.12.0 has been released!

* home: <https://github.com/seattlerb/zentest>
* rdoc: <http://docs.seattlerb.org/ZenTest>

ZenTest provides 4 different tools: zentest, unit_diff, autotest, and
multiruby.

zentest scans your target and unit-test code and writes your missing
code based on simple naming rules, enabling XP at a much quicker pace.
zentest only works with Ruby and Minitest or Test::Unit. There is
enough evidence to show that this is still proving useful to users, so
it stays.

unit_diff is a command-line filter to diff expected results from
actual results and allow you to quickly see exactly what is wrong.
Do note that minitest 2.2+ provides an enhanced assert_equal obviating
the need for unit_diff

autotest is a continous testing facility meant to be used during
development. As soon as you save a file, autotest will run the
corresponding dependent tests.

multiruby runs anything you want on multiple versions of ruby. Great
for compatibility checking! Use multiruby_setup to manage your
installed versions.

*NOTE:* The next major release of zentest will not include autotest
(use minitest-autotest instead) and multiruby will use rbenv /
ruby-build for version management.

Changes:

### 4.12.0 / 2019-09-22

* 3 major enhancements:

  * Deleted autotest from project. Use minitest-autotest instead.
  * Removed multiruby_setup. Use ruby-install or ruby-build or install your own.
  * Update multiruby to use ~/.rubies (default for ruby-install).

* 4 minor enhancements:

  * Find and use the multiruby next to multigem.
  * multiruby ignores GEM_HOME and GEM_PATH (to allow multigem to work).
  * multiruby respects global `multiruby_skip` entries in `~/.hoerc`.
  * multiruby sorts versions properly so glob ordering is consistent.

* 1 bug fix:

  * Removed hacks for rbx because nobody uses rbx.