Travis CI build failing: unknown keywords: whitelist_classes, whitelist_symbols / bundle exec rake ci:metrics

[jm3]

https://travis-ci.org/dkubb/ice_nine/builds/463597880

unknown keywords: whitelist_classes, whitelist_symbols
/home/travis/.rvm/rubies/ruby-head/lib/ruby/2.6.0/psych.rb:328:in `safe_load'
/home/travis/.rvm/gems/ruby-head/gems/rubocop-0.60.0/lib/rubocop/config_loader.rb:185:in `yaml_safe_load'
...
rake aborted!
Rubocop not successful
/home/travis/.rvm/gems/ruby-head/bundler/gems/devtools-0483d867e0ec/tasks/metrics/rubocop.rake:8:in `block (2 levels) in <top (required)>'
/home/travis/.rvm/gems/ruby-head@global/gems/rake-12.3.1/exe/rake:27:in `<top (required)>'
/home/travis/.rvm/gems/ruby-head/bin/ruby_executable_hooks:24:in `eval'
/home/travis/.rvm/gems/ruby-head/bin/ruby_executable_hooks:24:in `<main>'
Tasks: TOP => ci:metrics => metrics:rubocop
(See full trace by running task with --trace)
The command "bundle exec rake ci:metrics" exited with 1.```