Ruby 2.6 Support?

```
NotImplementedError: Please switch to Ruby 1.9's standard CSV library.  It's FasterCSV plus support for Ruby 1.9's m17n encoding engine.
from /Users/christopherhough/.rbenv/versions/2.6.6/lib/ruby/gems/2.6.0/gems/fastercsv-1.5.5/lib/faster_csv.rb:13:in `const_missing'
```