Update ruby-jekyll-coffeescript to 2.0.0.
2.0 / 2019-09-06
Major Enhancements
* Require Ruby 2.4 or greater (#38)
* Require Jekyll 4.0
1.2.2 / 2019-03-24
Bug Fixes
* Revert jekyll to be just a development_dependency for v1.x.x series.
1.2.1 / 2019-03-23
Bug Fixes
* Re-introduce Ruby 2.3 support and test Jekyll 3.7+ (#33)
1.2.0 / 2019-03-22
Development Fixes
* Drop support for Ruby < 2.4
* Allow Jekyll v4 (still alpha)
* Style: Target Ruby 2.4 (#31)