Log Message:
devel/ruby-mixlib-cli: update to 2.1.5

Update ruby-mixlib-cli to 2.1.5.

2.1.5 (2019-12-22)

* Use our standard rakefile #68 (tas50)
* Fix chef-style #71 (vsingh-msys)
* Add windows PR testing with Buildkite #73 (tas50)
* Test on Ruby 2.7 + random testing improvements #75 (tas50)

2.1.1 (2019-06-10)

* Don't explode when there are unknown keys in 'config' #66 (marcparadise)

2.1.0 (2019-06-07)

* Setup BuildKite for PR testing #61 (tas50)
* Disable Travis testing & Update codeowners #62 (tas50)
* Fix gem homepage url #64 (tsub)
* [MIXLIB-CLI-63] Add deprecated_option support #65 (marcparadise)

2.0.6 (2019-05-14)

* Add additional github templates and update codeowners #58 (tas50)
* Improve the --help text output of 'in:' #59 (btm)
* Print out human readable lists of allowed CLI options #60 (tas50)

2.0.3 (2019-03-20)

* fix global state pollution issues across examples #54 (lamont-granquist)
* Add back support for Ruby 2.4 #56 (tas50)

2.0.1 (2019-01-04)

* Don't ship the test files in the gem artifact #51 (tas50)

2.0.0 (2019-01-04)

* remove hashrockets syntax #43 (lamont-granquist)
* Remove require rubygems #44 (tas50)
* Update testing and contributing boilerplate #45 (tas50)
* More testing / release boilerplate #46 (tas50)
* Update codeowners and add github PR template #47 (tas50)
* Lint the example code #49 (tas50)
* update travis, drop ruby < 2.5, major version bump #52 (lamont-granquist)
* actually do the major version bump #53 (lamont-granquist)