Suppress keyword arguments warnings in Ruby 2.7

[pocke]

It suppresses keyword arguments warnings in Ruby 2.7. And it works well with Ruby 2.8 (the master branch).

Problem

I18n-tasks displays warnings on Ruby 2.7.
I found the following warnings with bundle exec rake.

/path/to//glebm/i18n-tasks/spec/file_system_data_spec.rb:88: warning: Passing the keyword argument as the last hash parameter is deprecated
/path/to//glebm/i18n-tasks/spec/file_system_data_spec.rb:123: warning: Passing the keyword argument as the last hash parameter is deprecated
/path/to//glebm/i18n-tasks/lib/i18n/tasks/data/tree/siblings.rb:276: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call
/path/to//glebm/i18n-tasks/spec/support/trees.rb:20: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call
/path/to//glebm/i18n-tasks/lib/i18n/tasks/data/tree/traversal.rb:154: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call
/path/to//glebm/i18n-tasks/spec/support/keys_and_occurrences.rb:13: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call

And the test fails on Ruby 2.8.

Solution

Add ** to keyword arguments, etc.
see https://www.ruby-lang.org/en/news/2019/12/12/separation-of-positional-and-keyword-arguments-in-ruby-3-0/

And this pull request also enables Ruby 2.7 on Travis CI.